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Meteorological Science

Compilation of  Q & A format of the book Science and Technology for Civil Services Examinations, Tata McGraw Hill Publication

Chapter 34 Meteorological Science

1 . Weather forecasting is not an exact science. It’s primarily based on observation. But attempts are being made to make  it as scientific as possible. Comment 50 words  page 482
It is prediction of weather through application of the principles of Physics and gathering of meteorological statistical data. It is difficult to gather this data and this data keeps changing with changes in atmospheric conditions. The best of predictions may be vaid for two or three days after which predictions have to be revalidated.

2. What is synoptic meteorology? 483
It characterises the weather over a large region at exactly the same time in order to organise information about prevailing conditions. Synchronised observations for a specific time are plotted on a map for a broad area from which a general view of the weather in that region is gained.

3 . Describe the techniques adopted to gather meteorological data 100 words 484
Technological advance since the 1960s have led to a growing reliance on remote sensing, particularly the gathering of data with specially instrumented weather satellites as well as observations from ships, aircrafts, radiosondes and Doppler radar. This information is sent to meteorological centres where the data are collected, analysed and made into a variety of maps and charts.

To predict the weather by numerical means, atmospheric models have been developed by using mathematical equations to describe how atmospheric pressure, temperature and moisture will change over time. The equations are programmed into a computer which determines how different variables will change with time.

4. What is the window of meteorological deduction? 484
Weather forecasts made for 12 and 24 hours are typically quite accurate. Forecasts made for two to three days are good. Beyond about 5 days, the forecast accuracy falls off sharply.

5 . Describe the practical applications of weather forecasting. 100 words 484
Agriculture is a major area for use of weather forecasting. Planting and harvesting can be planned better if weather patterns are estimated. It is important in India due to the dependence of the agricultural sector on the monsoon. It has also become important for aviation and sea transport.

Many ocean going vessels as well as military ships use optimum ship routing forecasts to plan their routes in order to minimise lost time, potential damage and fuel consumption in heavy seas. Airlines carefully consider atmospheric conditions when planning long flights so as to avoid the strongest head winds and ride with the strongest tail winds.

Marketing stores require weather forecasts to help with the timing of sales and products ranging from snow tyres to summer clothes. International trading of foodstuffs such as sugar, wheat, corn and coffee can also be severely affected.

6 . How many regional centers  of Meteorological observation are there 485
There are 6 at New Delhi, Mumbai, Kolkata, Chennai, Nagpur and Guwahati.

7 . What s the significance of INSAT? 485

India was the first developing country in the world to have its own geo-stationary satellite, INSAT, for continuous weather monitoring of this part of the globe and particularly for cyclone warning.

8 . Describe the major achievements  of  the (IMD) Indian Meterological Department. 100 words. /486
It has Doppler weather radars installed for more accurate weather forecasting; installation of 100 Digital Cyclone Warning Dissemination systems along the Andhra coast; a Mountain Meteorology Centre was established at Delhi for prediction of avalanches, flash floods and landslides; a new long range prediction model that gives July rainfall for helping Kharif crop sowing; lowering of detection and response times by upgrading the seismic monitoring system.

An Earthquake Risk Evaluation Centre was established at Delhi for seismic micronization. There are also customised forecasts for various other important applications like power distribution, water resources, defence, emergency response and adventure sports.

9 . What are the Agro Advisory services rendered by the IMD 486
It has developed a new long range prediction model that gives more lead time as well as July rainfall as an additional forecast for helping Kharif crop sowing.

10 . What s NCMRWF? Describe it’s vision 50 words 486
The NCMRWF (National Centre for Medium Range Weather Forecasting) was established as the premier institution in India to provide medium range weather forecasts and to render agro advisory services to farmers.

its vision is to become the preferred choice for NWP (Numerical Weather Prediction) guidance over the Indian monsoon region , to develop an earth weather modelling and assimilation system, especially for the monsoon system, to develop newer applications and reach out to society at large, and constantly striving to improve accuracy and consistency.

11 . What is global modeling? 487
NCMRWF runs 2 global spectral models (T-80, T-170) which produce daily global forecasts. The horizontal resolution of these models are 150km and 75km respectively. The atmospheric system they attempt to predict is chaotic. An ensemble prediction system, which involves generation of multiple forecasts as a function of the uncertainty has been developed.

12 . What is Mesoscale modelling? 487
They are essential for accurate prediction of high impact weather such as severe thunder storms, mountain weather forecasts, cloudbursts and cyclones. The mesoscale models (MM5 & ETA) are run up to 72 hours on real-time for high impact weather prediction using initial and boundary conditions from the global forecast model.

13 . What are extended range forecasts? 50 words 488

Currently, the dynamic approach is used for extended range (monthly) prediction based on simulations from the global atmospheric model. Probability of occurrence of excess, normal or deficient rainfall for 6 homogenous regions of the country is calculated.

A more accurate couples system is being developed to understand and predict the monsoon environment a season in advance. Experiments are being conducted to reduce model systematic errors and uncertainties.

14 . What  are Ocean State forecasts? 488
They are in great demand for ship routing, fisheries, tourism, oil exploration and port and naval operations. Ocean surface parameters form global and mesoscale models derive most of the ocean and wave models in the country in both real time and research mode. NCMRWF runs a daily global ocean wave model to predict significant wave heights, peak wave direction and wave period.

15 . What are the goals of NCMRW?

It hopes to develop crop model based application tools for agro-advisories, use of remote sensing products to address variability within the agro-climatic zones, and precision farming using GIS.

16 . What s cloud seeding?

It involves seeding clouds with tiny particles to bring more precipitation from them. There two ways to seed clouds. The first uses the coalescence process of rain formation. Small water drops are injected into the base of a cloud, which grow in size by collision with other particles until they are heavy enough to fall down.

The second method employs the ice crystal process of rain formation where small particle of silver iodide are injected into a cloud. These particles act as ice crystals. Water vapour from the surrounding liquid droplets evaporates and freezes onto the iodide particles, which grow larger. The growing crystals eventually become heavy enough to fall as precipitation.

Earth Sciences in India

Compilation of  Q & A format of the book Science and Technology for Civil Services Examinations, Tata McGraw Hill Publication

Chapter 33. Earth Sciences in India

1. Describe India’s coast line, economic zone and continental shelf.  How far does the maritime belt , economic, belt and Fisheries belt extend.   Page (470, and 480)

India’s coastline sprawls over a distance more than 7500 km long, and its territory includes 1256 islands. Its exclusive economic zone covers about an area of 20 lakh sq.km and the continental shelf stretches up to 350 nautical miles from the coast.

The continental shelf comprises of the sea bed and sub-soil of the submarine areas that extend beyond its territorial sea throughout the natural prolongation of its land territory to the outer edge of the continental margin, or to a distance of 200M from the baselines from which the breadth of the territorial sea is measured, where the outer edge of the continental margin does not extend up to that distance.

Territorial waters, or a territorial sea, as defined by the 1982 United Nations Convention on the Law of the Sea ]is a belt of coastal waters extending at most 12 nautical miles (22 km; 14 mi) from the baseline (usually the mean low-water mark) of a coastal state. The territorial sea is regarded as the sovereign territory of the state, although foreign ships (both military and civilian) are allowed innocent passage through it; this sovereignty also extends to the airspace over and seabed below.

If the distance between two States is less than 24 miles, a line drawn midway is the Fisheries belt. Within this restricted territorial belt, the littoral state (adjacent state) has exclusive rights to fish)

An exclusive economic zone extends from the outer limit of the territorial sea to a maximum of 200 nautical miles (370.4 km) from the territorial sea baseline, thus it includes the contiguous zone. A coastal nation has control of all economic resources within its exclusive economic zone, including fishing, mining, oil exploration, and any pollution of those resources. However, it cannot prohibit passage or loitering above, on, or under the surface of the sea that is in compliance with the laws and regulations adopted by the coastal State in accordance with the provisions of the UN Convention, within that portion of its exclusive economic zone beyond its territorial sea. Before 1982, coastal nations arbitrarily extended their territorial waters in an effort to control activities which are now regulated by the exclusive economic zone, such as offshore oil exploration or fishing rights .Indeed, the exclusive economic zone is still popularly, though erroneously, called a coastal nation’s territorial waters.

Contiguous zone

The contiguous zone is a band of water extending from the outer edge of the territorial sea to up to 24 nautical miles (44 km; 28 mi) from the baseline, within which a state can exert limited control for the purpose of preventing or punishing “infringement of its customs, fiscal, immigration or sanitary laws and regulations within its territory or territorial sea”.

2. Describe the organization of Ministry of Earth Sciences. What areas are covered by it? 470/ 100 words
it was created in 2006 after merger of India Meteorological Department (IMD), National Centre for Medium Range Weather Forecasting (NCMRWF), Indian Institute of Tropical Meteorology (IITM), and Earth Risk Evaluation Centre (EREC) with the then ministry of Ocean Development.

The ministry’s mandate is to look after atmospheric sciences, ocean science and technology and seismology in an integrated manner. It has to formulate and implement programmes relating to long term economic and technological development. It seeks to create a framework for understanding the complex interactions among key elements of the earth system.

3. What services does the Ministry of Earth Sciences provide? 471
it provides the nation with services in forecasting the monsoon, ocean state, earthquakes, tsunamis and other phenomena related to earth systems. It also deals with science and technology for exploration and exploitation of ocean resources and play a nodal role for Antarctic/Arctic research.

4. Write a note in hundred words on the Antarctica Treaty
It came into force in 1961 after ratification by 12 countries then active in Antarctic science. The treaty covers the area south of 60 degree south latitude. Its objectives are to demilitarise Antarctica, to establish it as a zone free of nuclear tests and disposal of radioactive materials, and to ensure that it is used for peaceful purposes only; to promote international scientific cooperation in Antarctica; and to set aside disputes regarding territorial sovereignty.

The treaty remains in force indefinitely. 44 countries have acceded to it. 27 nations, including India have consultative status. They have adopted over 200 recommendations and negotiated 5 separate international agreements, collectively, these are known as the Antarctic Treaty System (ATS).

5 . What is the significance of Antarctic Research? 100 words 471-472
Antarctica provides great scope for the conduct of scientific research for the benefit of mankind. It is an impressive, pristine laboratory which has enabled scientists and researchers to detect and monitor global environment phenomena such as depletion of the ozone layer, global warming, and sea level changes. It has supplied data crucial to weather forecasting in the southern hemisphere.

Glaciological research provides important data about the heat exchange budget. The earth’s geomagnetic field renders Antarctica especially suitable to the study of polar terrestrial interactions and cosmic rays that travel from outer space.

The continent’s environment provides unique opportunities to study the specialised adaptations of organisms. Human biology and medicine provides information on the physiological adaptation of man to extreme climates and isolation.

6 . Describe in hundred words the Indian Antarctic Research Programme.
It began in 1981, when the first Indian expedition was flagged off from Goa. Subsequently, 25 expeditions have been undertaken, including one to the
Wedell sea and another one to the Southern Ocean for krill ( a kind of fish) exploration.

MAITRI, the Indian station is situated in the Schirmacher Oasis. It has all modern facilities to carry out research in various disciplines such as biology, earth sciences, glaciology, atmospheric sciences, meteorology, cold region engineering, communication, human physiology and medicine. It has a capacity to accommodate 25 people in the winter.

India was admitted to the Antarctic treaty in 1983. It was admitted as a member of the Scientific Committee in Antarctic Research (SCAR) in 1984. India became a member of the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) in 1986 and built its second permanent station ‘Maitri’ in 1988-89.

7 . Describe the activities of the National Centre for Antarctic and Ocean Research (NCAOR)  473

It was established as an autonomous institution in 1998. It is designated as the nodal organisation for the co-ordination and implementation of the Indian Antarctic Programme, including the maintenance of India’s permanent station in Antarctica, Maitri.

8 . What are the activities of the National Institute of Oceanography? 100 words 474
It was established in 1966. The principal objective is to develop sufficient knowledge related to physical, chemical, and biological aspects of the seas through the study of physical process in the ocean including the monsoon, exploration of living resources of the sea, sea-farming technology, bio-active substances from marine plants and animals, development of offshore oilfields, deep sea exploration of minerals, coastal zone and harbour development, studies for effective control of marine pollution, ocean modelling, processing of satellite imagery data and acoustic topography.

The institute is also involved in R&D projects for exploration and utilisation of natural resources of the seas.

9 . What is the Coastal Zone and Islands Programme? 50 words 475
The main aim of this programme is to provide basic data and information required for the effective management of the marine environment, its conservation and develop technological aids for harnessing its resources. To address these issues, we have—

COMAPS (Coastal Ocean Monitoring and Prediction System) envisaging systematic monitoring and modelling of the marine pollution along the coastline.

SELAM (Sea Level Measurement Programme) for precision sea level measurements using modern tide gauges.

Island Development Programme- development of aquaculture techniques to improve the quality of lives in the islands.

10 . Describe India ‘s Ocean Research. 100 words 476

It is being focussed on multi-disciplinary research on the physical, chemical, geological and biological aspects of the Indian Ocean. Ocean vessels can also be used for campaigns in validating satellite oceanographic data, assessment of marine resources and for various technology demonstration activities.

Dedicated cruises were also undertaken for summer monsoon and winter monsoon coverage of the Bay of Bengal as well as the Andaman sea. A centralised FORV (Fisheries Oceanographic Research Vessel) Data and Referral center has been set up at Kochi. Survey and exploration of poly-metallic nodules is also being carried out in about 100 blocks to refine resource estimation further and to identify first generation mine sites.

With a view to protecting and preserving the marine environment, the quality of coastal waters is being continuously assessed at many locations along the coast. The two indigenously built coastal vessels- Sagar Purvi and Sagar Paschimi are being utilised for continuous monitoring of pollution levels in the coastal areas.

Sagar Kanya and Sagar sampada have been carrying in surveys for discocering economic resources of India’s exclusive economic zone.

11 . What is the National Data Buoy Programme? 100 words  476
Collection of time series observations of oceanographic and surface meteorological parameters over Indian seas are necessary to improve oceanographic services and predictive capability of short-term and long-term weather/climatic changes. The National Data Buoy Programme was started in 1997 for such observations.

These data buoys carry sensors to measure wind speed, wind direction, air pressure, air temperature, conductivity, sea surface temperature, current speed, current direction, and wave parameters. The buoys are equipped with global positioning system, beacon lights and satellite transceivers. Some buoys can measure parameters like radioactivity, light attenuation in three wavelengths and dissolved oxygen. Power to the buoys is provided by solar panels and chargeable battery packs.

Applications of this programme include Environmental impact assessment, Meteorology, oceanography, fisheries, validation of satellite data, offshore installations, ports and coastal structures, and shipping.

12. Marine organisms have attracted attention as a potential source for drugs. Explain in 100 words 477
Dozens of promising products, including cancer therapy made from algae and a painkiller taken from snails, are in development at research laboratories. Other products, such as an anti-inflammatory drug extracted from the Caribbean sea whip, and a potential antiosteoporotic drug of hexacoral origin are under review.

Among other areas of research are the discovery, development and production of drugs from marine bacteria, fungi, microalgae, sponges and opisthobranch molluscs.

After successful completion of clinical trial, the systematic collection, extraction and biological evaluation of seaweeds, mangroves, anemones, sponges, starfish, seahorses would be carried out to identify other potential drugs. Product development is on-going in 7 areas- anti-diabetic, anti-hyperlipidaemic, anti-anxiety, anti-hyperglycaemic, anti-bacterial, anti-tumour and larvicidal.

13. What is COMAPS? 478
The Coastal Ocean Monitoring and Prediction System (COMAPS) has been in operation at 82 locations for collection and analysis of 25 parameters relating to physical, chemical and biological characteristics of water and sediments. Based on this data, the areas of concern have been identified and steps are being taken to prevent and control the causes of pollution.

14 . What are submersibles? 478
A submersible is a small vehicle designed to operate underwater. A feasibility study has been carried out regarding the possibility of developing indigenous submersibles capable of operating at a depth of 600m in the first phase and 2500m in the second phase.

15. Describe the integrated coastal and marine area management Programme (ICMAM)? 50 words. 478
The programme has two components, namely capacity building and development of infrastructure for R&D, Survey and Training for ICMAM. The second component covers 4 activities- development of GIS (Geographic Information System) based information system for 11 critical habitats in the coastal and marine areas, determination of waste assimilation capacity at selected estuaries along the coast, development of guidelines for environmental impact assessment and preparation of model integrated coastal and marine area management plans.

16.  What are polymetallic nodules? Describe the activities in this field? 100 words
Polymetallic modules on the ocean floor are considered to be a treasure house of much needed metals. The potato shaped, largely porous modules, are found in abundance carpeting the ocean floor. The nodules are of economic importance because they contain, besides manganese and iron, nickel, cobalt, copper, lead, molybdenum, cadmium, vanadium, titanium, of which cobalt, copper and manganese are considered to be of strategic importance.

In August 1987, India became the first country to be allotted 150,000 sq. km of area in the central Indian ocean for exploration and exploitation of polymetallic nodules under certain obligations and was given the status of a Pioneer Investor. The Department of Ocean Development which has been designated as the nodal agency responsible for implementing the deep seabed mining programme, has drawn up a long term plan to fulfil these obligations.

17 . What are the important types of marine data being studied now? 481
The important types of marine data being studied now are bathymetry data, seismic reflection data, seismic refraction data, gravity and magnetic data and geological knowledge.

18 . How are Tsunami warnings given ? (482)

After the devastating Indian Ocean Tsunami, the Department of Ocean Development was given the responsibility of putting in place an early warning system for tsunami and storm surges in the Indian Ocean region with an ultimate objective of saving lives and property. The total cost of this system has been estimated at 125 crores of rupees and is expected to become operational by 3 years,

Physics and Global Environmental issues

Compilation of  Q & A format of the book Science and Technology for Civil Services Examinations, Tata McGraw Hill Publication

1 . What is Photonics? How is it different from Electronics ?  What is the use of Photonics?
Photonics is the study of light, including its generation, propagation and interaction with matter, where light includes more than just visible wavelengths. In photonics, energy and information are carried by photons rather than electrons as in electronics. Photonics use the wave/particle nature of light to create high technology optical materials. They are expected to replace electronic components with optical components

2 . How does Photonics help computers?
It could lead to much higher memory capacities and a significant increase in data processing speed.

3 . In about a hundred words explain the applications of Photonics?
It can be used for bio-medical sensors and instrumentation and capillary electrophoresis, digital multimeters, power supplies, microwave systems, detection of cracks and corrosion under paint, carrier grade data networks, high-performance internet services and telecom networking products. It can be used for Industrial Process Control, Instrumentaion and Telecom. In Industrial Process Control, we can hace accelerated component life8testing equipment, Lab on a chip etc., In Telecon we can have high performance , intelligent and value added systems. In Instrumentation systems we can detect cracks and corrosion under paint. This work led to prototype detection devices for use on airplane wqings that are in the process of being brought to the market.

4 . Explain in a hundred words the medical uses of Photoncs.
Optical sensors that use photons as sensing elements are becoming increasingly important in the field of non-invasive diagnostics. Spectroscopic techniques are used for minimally invasive early detection of cervical, prostrate, oral and gastro-intestinal cancers. Photoplethysmography (PPG) is a non-invasive method for detecting the blood volume pulse. This information is analysed afrer interfacing with a computer. The bacteria and virus detection defence technology recognises the spectroscopic signatures of bacteria and viruses. Scientists are also developing a sophisticated photonic pill called the compact photonic explorer, that can perform remote diagnostics in the digestive tract and send information back to doctors.

5 . What is Laser?
Laser is a device that produces a very narrow, powerful beam of light. A laser beam can also be transmitted over long distances with no loss of power.

6 . What are the components of Lasers?
A typical laser contains 4 primary components-The active medium may be solid crystals such as ruby. They contain atoms whose electrons may be excited to an elevated energy level by an external energy source. The excitation mechanism or energy source pumps energy into the active medium .A high reflectance mirror at the ends of the optical cavity reflects essentially 100% of the laser light. There is also a mirror that reflects less than 100% of the laser light and transmits the remainder.

7 . Why is laser called coherent light?
A laser produces a thin, intense beam of light which is highly directional. Hence, it is also referred to as coherent light.

8 . What is class 1 laser? 412
A class 1 laser is considered safe for humans. This class includes all laser systems which cannot emit levels of optical radiation above the exposure limit for the eye under any conditions inherent in the design of the laser product.

9 . What is class 2 laser? When is it hazardous?
A class 2 laser system must emit a visible laser beam. Because of its brightness, it will be too dazzling to stare into for extended periods. Momentary viewing is not considered hazardous as the upper radiant power limit of this type is less the MPE (Maximum Permissible Exposure) for an exposure of 0.25 second or less. Intentional extended viewing is however harmful.

10 . What is class 3 laser? Is it harmful to the skin? When does it cause harm?
A class 3 laser system can emit any wavelength, but it cannot produce a diffuse (not mirror-like) reflection hazard unless focussed or viewed for extended periods at close range. It is also not considered a serious skin hazard or fire hazard.

11 . How is laser useful in IT? 100 words
Lasers are particularly useful in recording, storing and transmitting information. The most common use is recording of music and motion pictures on compact disks. Bursts of laser light record such information on the disks in patterns of tiny pits. The laser beam’s tight focus allows much more information to be stored on a CD or DVD . Lasers can also read and play back information stored on these disks. In a CD or DVD, the laser beam reflects off the pattern of pits as the disk spins. Other devices in the player change the reflection into electrical signals and decode them as music.

12 . What is holography?
Laser beams can produce three-dimensional images in a photographic process called holography. Holography is a method for storing and displaying a three-dimensional image, usually on a photographic plate or any light-sensitive material. The exposed plate is called a hologram. Some credit cards contain holograms to prevent counterfeiting,

13 . How does a Laser printer work?
Laser printers use a scanning laser beam to produce copies of documents. Scanning involves movement of a laser beam across a surface. In a supermarket, what looks like a line of light is actually a rapidly moving laser beam scanning a bar code. A bar code consists of a pattern of lines and spaces that identifies a product.
14 . How are lasers useful in Medicine? 100 words
In medicine, the heating power of laser is often used in eye surgery. Highly focussed beams can close off broken blood vessels on the retina. It can also reattach a loose retina. Laser beams pass through the cornea but cause no pain or damage because the cornea is transparent and does not absorb light. Lasers are also used to treat skin disorders, remove birthmarks and shatter gallstones. Lasers can replace the scalpel, in some operations. They reduce bleeding and damage caused to nearby healthy tissues.

15. How are laser light shows created?
Laser light shows are created with scanning laser beams. The beams move so rapidly they produce what looks like a stationary picture. They can thus produce very colourful visual effects.

16 . How are lasers useful in ophthalmology?
The heating power of laser is often used in eye surgery. Highly focussed beams can close off broken blood vessels on the retina. It can also reattach a loose retina. Laser beams pass through the cornea but cause no pain or damage because the cornea is transparent and does not absorb light.

17 . What is a miniature hydrogen bomb explosion? 
In nuclear research, scientists use lasers to create controlled, miniature hydrogen bomb explosions. They focus many powerful laser beams onto a pellet of frozen forms of hydrogen. The intense beams compress the pellet and heat it to millions of degrees. This causes the nuclei to fuse and release energy.

18 . What is a pico second or femto second ?
A pico second is 10-12 seconds. A femto second is 10-15 seconds.

19 . What is line width and how  are lasers relevant here?
By careful design of the laser components, the purity of the laser light (measured as the line width) can be improved more than the purity any other light source. This makes the laser very useful for spectroscopy. It also makes techniques like Raman spectroscopy possible. It can also be used to make extremely sensitive detectors of various molecules.

20 . What is spectroscopy?
Spectroscopy is the study of interaction between matter and radiated energy.

21 . How are lasers helpful in measuring earthquakes and land surveys?
Laser beams directed over long distances can detect small movements of the ground. Such movements help geologists involved in earthquake warning systems. Laser devices used to measure shorter distances are called range finders. Surveyors use the devices to get information needed to make maps.

22. What are optical tweezers?
Optical tweezers involve grabbing, moving and generally manipulating, without any physical contact, micrometre-sized particles. This is based on the optical dipole or gradient force. They are based primarily on Newton’s laws and fundamental optics, and this has enabled an unprecedented insight into biological molecules such as the DNA.

23 . What exactly is Photonics?
Photonics deals with generating, controlling and detecting light and is based on a variety of materials. It also plays a major role in sensing.

24 . The human vision system is the ultimate interface between electronics and photonics. Explain
The eye and the brain work in perfect harmony. We sense others by photons, the quantised light waves that impinge on the retina. The optical information received by the retina is quickly converted into electrical impulses. These impulses travel through the optic nerve to the visual cortex of the brain.

25 .  What is EPIC?
Seamless union of electronics and photonics is the ultimate goal of the program for developing a single tiny chip of silicon that can not only manipulate and guide photons, but also convert photons into electrons and process the electrical signals. This program is called EPIC. It seeks to produce a single chip capable of emulating the eye and the brain.

26 . Describe the Photonics Development Programme in India 50 words. 417 -418
Its short term objective is to nurture photonic technologies, including those that are relevant to IT and optical communications such as optical fibres, optical amplifiers. The long term objective of the programme is to ensure that India has a presence as a technology developer in the broader application domains of photonics that include polymers used in nano-photonics and photonic crystal fibres, besides having a presence as an optical communication developer.

Chapter 31 Global Environmental issues

1 . Describe the Stratospheric  Ozone layer . 50 words
The stratospheric ozone layer is found in a broad band, generally extending from about 15 to 35 km above the earth. The profile and concentration of this layer depends on the dynamics of the winds, as well as sunlight and trace pollutants. The layer is surprisingly thin. But it is sufficient to filter out the bulk of the ultraviolet radiation that would otherwise reach the earth’s surface.

2 . What is the importance of this layer?   100 words
Life on earth evolved under the protection of an ozone layer thick enough to remove much of the UV-B radiation known to damage cellular DNA. YV-B rays are of high energy, which allows them to penetrate deeply into water, leaves and skin. It can harm metabolism of cells and damage genetic material. It could lead to increased incidence of skin cancer, eye damage and cataracts as well as inhibition of the immune system. Less stratospheric ozone also means less local heating. A weakened Ozone layer has also effects on climate. It could lea to decreased crop yields, damage to forst eco systems etc.,

3 .  What is stratospheric Ozone Destruction.? What are its consequences? 100 words
Ozone can be destroyed by chemicals that react with it directly, or by those that react with the oxygen atom temporarily freed when an ozone molecule splits. But, the only ozone destroyers of concern are those that can participate in a catalytic cycle, where one trace catalytic chemical can be responsible for destroying hundreds of thousands of ozone molecules. The detection of significant concentrations of CFCs in the lower atmosphere was coupled with the finding that photochemical and rain-out processes that usually remove most pollutants were not working for these compounds. They are extremely stable and have atmospheric lifetimes of 50 to several 100 years. Lesser stratospheric oxygen means less local heating, and that more ultraviolet light is transmitted to the earth’s surface causing skin cancer and damage to genetic material.

4. What is the Ozone Hole? What are its effects? 424
A massive continental-sized hole appeared over the continent of Antarctica in the spring of 1980. In the 1990s, this hole grew in size. The polar vortex was also responsible for the formation of the ozone hole. The winter stratospheric air over Antarctica is colder than the air elsewhere, which results in the formation of polar stratospheric clouds. This is because the strong confining winds of the polar vortex isolate this air from the warmer lower-altitude air. These cause greater chemical reactions and these chemicals are released during spring which in turn destroys the ozone. Lesser stratospheric oxygen means less local heating, and that more ultraviolet light is transmitted to the earth’s surface causing skin cancer and damage to genetic material.

5 . What is the Montreal  Protocol?424
As evidence emerged on the extent of the threat to the ozone layer, the international community agreed to control ozone-depleting substances and schedule a time-table for completely phasing them out. This agreement is known as the Montreal Protocol.

6 . What are the threats to the Ozone Layer apart from those caused by industry? 50 words  425
The solid rocket strap-on motors used in the most powerful launch systems, such as Ariane, produce copious amounts of HCL. A significant fraction of their exhaust gases is deposited in the stratosphere.. The plume from each launch causes a temporary mini ozone hole.

The chemicals that are replacing CFCs are HCFCs and HFCs. Though they have less chlorine in them as compared to CFCs, they are still ozone-depleting substances.

7 . What are the present threats to bio-diversity?
The present threats are overexploitation of resources such as hunting, introduction of foreign species including predators and diseases and environmental pollution. The most common threat is loss of habitat, due to deforestation, pollution of wetlands and ploughing up of Prairies.

8 . Describe the extent of Massive extinction of modern times.  426-427/50 words
Massive extinctions have occurred 5 times in the earth’s history, most notably 65 million years ago, when 15% of the species including dinosaurs were wiped out. There is strong evidence that we are in the opening phase of the 6th massive extinction. This extinction is unprecedented in both its breadth and speed. In the past 10,000 years, and especially in the last 500, the rate of extinction of species has increased to somewhere between 100 and 1000 times what it was before human history began.

9. What are the benefits of Biodiversity  to  humans? 100 words. 427-428
We derive many benefits from biodiversity. We get useful products from the wild. Nearly 25% of the drugs used today originally came from plants. One famous example is the anti-cancer drug taxol which was originally extracted from the Pacific yew. Other well-known discoveries from plants include quinine, penicillin and aspirin. It is also important to conserve genetic diversity within individual species. The breeding of new strains of pest-resistant crops and livestock is critically dependent on the supply of new genetic variability. This variability has been provided to scientists by wild relatives of domesticated plants and animals.

10 . Benefits of biodiversity conservation come from ecosystems and services. Comment 428
Soil nitrogen, a key element for agricultural productivity, depends on bacteria such as rhizobium, which live in the roots of leguminous plants. Micro-organisms also have the ability to carry out chemical reactions. A major breakthrough in genetic engineering- the polymerase chain reaction technique used to make copies of DNA- was possible because of the discovery of heat-stable enzymes in bacteria living in hot springs.

11. What is the value of Diverse Ecosystem?
Wetlands such as swamps, marshes and mangroves filter large quantities of pollutants from the water. They also serve as breeding grounds for fish, and are thus vital to the productivity of lakes and oceans. Forests and grasslands also absorb pollutants from industries and help purify the air. Plants too need a variety of micro-organisms to grow: bacteria and algae for nitrogen and fungi for phosphorus.

12 . What is the future of biodiversity? 100 words429
Steps have to be taken to stem the tide of the sixth extinction. An international treaty called CITES (convention on international trade in endangered species of flora and fauna) went into effect in 1975 to outlaw the trade of endangered animals and animal parts.

One of the key agreements adopted in Rio in 1992 was the Convention on Biological diversity. It established 3 main goals: the conservation of biological diversity, the sustainable use of its components, and the fair and equitable sharing of the benefits from the use of genetic resources. Preserving endangered eco-systems is an important way to protect the endangered species within them.

13 . What is Green House Effect? 430
Greenhouse effect is the warming of the lower atmosphere and surface of a planet. When the radiation from lands and seas strike certain gases, these substances absorb the heat and become heated. They are then cooled by sending out infrared rays of their own. Some of these rays come back to the earth’s surface, adding to the warming of the earth and the lower atmospheric levels.

14 . What is the relation between Green House Gases and Climate Change?  50 words
Since the 19th century, the amount of carbon-dioxide has increased by 25%, chiefly due to burning of fossil fuels. This and other greenhouse gases absorb the radiation from the earth’s surface, most of which is reflected back to the earth. This increases the temperature of the earth. This could lead to rising sea levels, greater severity of storms, and changing ocean and wind patterns. This affects agriculture, forestry and wildlife.


Nano Science and Nano Technologies

Compilation of  book Science and Technology for Civil Services Examinations, Tata McGraw Hill Publicaton

Chapter 28 Nano Science and Nano Technologies

1. Distinguish between NANO Science  and NANO technology
Nanoscience is the study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales, whose properties differ significantly from those at a larger scale.

Nanotechnology is the design, characterisation, production and application of structures, devices and systems by controlling the shape and size at the nanometer scale.

2. What is the size of a Nano meter, the human hair, a blood cell and an atom?
One nanometer(nm) is one-billionth of a meter. 1 nm = 10-9 m.

A human hair is approximately 80,000 nm wide, a red blood cell is approximately 7000 nm wide, and atoms are below a nanometer in size.

3. What did Feyman mean when he said that there is plenty of room at the bottom?
By this, Feynman meant that there is immense possibility of manipulating materials at the scale of individual atoms and molecules. It is akin to the whole of the Brittanica Encyclopedia written on the head of a pin.

4. How is Nano technology useful in cells and batteries?
An increase in surface area (per unit mass) will result in an increase in chemical reactivity, making some nano-materials useful as catalysts to improve the efficiency of fuel cells and batteries.

5 . Give examples of Nano  technology  occurring naturally
Milk is a nanoscale celluloid. There are more sophisticated examples such as nano-sized and nano-structured proteins that control a range of biological activities such as flexing muscles, releasing energy and repairing cells. Nano-particles are also naturally created in the process of combustion and food cooking.

6. Distinguish between top down and bottom up technologies on Nano technology.
Top-down techniques involve starting out with a block of material, and etching or milling it down to a desired shape. Bottom-up involves the assembly of smaller sub-units (atoms or molecules) to make a larger structure.

7. Distinguish between Nano technology and Micro technology
1 micrometre (micron) is equal to 1000 nanometres. The application of micro-technology is generally far closer to the market as compared to nano-technology. Micro-technology has been commercially exploited for many years, such as in the production of small, powerful computers.

8. What are carbon Nano tubes? 390
Carbon nano-tubes (CNTs) were first observed by Sumio Iijima in 1991. They are extended tubes of rolled graphene sheets. They are of 2 types- single-walled (one tube) and multi-walled (several concentric tubes). They have novel physical and chemical properties. They are mechanically very strong and are very good conductors of electricity.

9. What is a fullerene?
In the mid 1980s, a new class of carbon material was discovered called carbon 60 (C60). These are spherical molecules about 1nm in diameter, comprising 60 carbon atoms arranged as 20 hexagons and 12 pentagons, which is the configuration of a football. Some applications of fullerene are production of miniature ball bearings to lubricate surfaces, drug delivery vehicles and in electronic circuits.

10. What are Dendrimers?
Dendrimers are spherical polymeric molecules, formed through a nano-scale hierarchical self-assembly process. There are many types of dendrimers. They are used in conventional applications such as coatings and ink.

They have a range of interesting properties. They can act as nano-scale carrier molecules and as such could be used in drug delivery. Dendrimers can assist environmental clean-up as they can trap metal ions, which could then be filtered out of water through ultra-filtration techniques.

11. Energy is equal to wave length or colour. What does this mean?
Energy is related to wavelength or colour. This means that the optical properties of the particle can be finely tuned depending on its size. Thus, particles can be made to emit or absorb certain wavelengths (colours) by controlling their size.

12. Describe some of the  applications  of Nano technology already in use.
Nano-particles are used in the production of carbon nano-tube based tennis racquets, burn dressings and dental fillings. Nano-sized titanium dioxide and zinc oxide are used in sunscreens, as they absorb and reflect the UV radiation. They are also used in composites, which are materials that combine separate components such that they have the best properties of each component.

Carbon fibers are used in polymers to enhance conductivity. A particular type of nano-composite is where nano-particles are used as fillers in a matrix, such as carbon black which is used as a filler to reinforce car tyres.

13. What are clay particles? What is their use?
Clays containing naturally occurring nano-particles have long been important as construction materials. Clay particles based composites – containing plastics and nano-sized flakes of clay- are used in car bumpers.

14. Describe in hundred words some of the future uses of Nano technology.
In the next five years, nano technology could be used in computer hard-disks, self-cleaning windows, better photovoltaic devices for renewable energy sources, anti-corrosion coatings and non-invasive molecular imaging in medicine.

Over the next 5-15 years, they could be used in semi-conductor lasers for telecommunication, high density data storage, better medical implants and artificially created organs and better sensors for pollutants.


14. What is the danger to human health from Nano technology?
There is evidence that suggests that some of the manufactured nano-particles could be more toxic per unit mass than larger particles of the same chemical. Also, it seems that nano-particles can penetrate cells more readily than larger particles. If nano-particles penetrate the skin, they might facilitate the production of reactive molecules that could lead to cell damage. There is also evidence to suggest that combustible nano-particles might cause an increased risk of explosion because of their increased surface area and potential for enhanced reaction.


15. Describe the social and ethical issues arising out of Nano technology in 100 words
The convergence of nano-technology with information technology could result in increased personal safety and security. It could also be equally used for covert surveillance, or for the collection and distribution of information without adequate consent.

As new forms of surveillance and sensing are developed, further research and expert legal analysis might be necessary to establish whether current regulatory frameworks and institutions can provide appropriate safeguards to individuals and groups in society. Bio-terrorism could get a boost with the fusion of nano-technology with chemistry. Nano-technology could even be used to re-engineer human beings.

16. What is the impact of Nano Technology on warfare 100 words 394
In the military context, nano-technology holds potential for both defence and offence. They could be used to produce more lethal weapons that are much harder to detect than the weapons that are currently being used. Mind-machine interfaces could enable pilots and soldiers to control high-tech weapons by thought alone. ‘Cognitive feedback helmets’ allow remote monitoring of soldiers’ mental state. Pulse weapons and other nuero disrupters could play havoc with enemy soldiers’ thought processes. New drugs could be produced which could enable soldiers to go without sleep for days, to suppress fear, or to repress psychological inhibitions against killing.

17. Describe India ‘s National Mission on Nano Science and Technology. 150 words. 394
In 2004, President Kalam organised a meeting of nano-science experts to devise a national mission plan. Its recommendations included spending US$22m each year for the next 5 years on 5 new national facilities specialising in complimentary areas of nano-technology and 10 mini-centres across the country.

The President also called for a dynamic task force to identify important national projects and set deadlines for achieving results in areas such as drug delivery systems for cancer and HIV/AIDS.

It is in this background that the GOI in 2007 approved the launch of a mission on Nano Science & Technology (Nano Mission). The New Millennium Indian Technology Leadership programme is also promoting two public-private collaborative ventures for developing nano-technologies that target drugs to exactly where they are needed in the human body.

A national center for nano-materials has been set up at the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI) in Hyderabad.

18. What are the prospects of Nano Technology in India. 100 words
With the core competence of IITs and Indian R&D institutions in collaboration with international institutions and industries, we can create joint venture organisations for many nano-technology products in water, energy, agriculture, health-care, space and defence. But far greater investment is required for this. The Nano Mision may provide the required financial impetus. With the Government approval for this mission, research in nano-science and technology in India appears to be poised for a renewed take-off.

 

Super Conductivity

(Summary of TMH book on Science and Technology for UPSC CSE preparations)

1 . What is Cryogenics? How does it help Doctors? 50 words 
How does it help Physics?
Cryogenics is the study of extremely low temperatures. It include the development of techniques that produce and maintain such temperatures for industrial and scientific use.

Cryogenics has provided doctors with ways to freeze living parts of the body, such as blood and eye corneas, for future use. Other medical uses of cryogenics include freezing organs during operations and destroying diseased tissues.

2. What is absolute zero?
Absolute zero, is theoretically the lowest temperature a gas can reach. It is equivalent to 0 kelvin or minus 273.15 degree Celsius.

3. What is liquid air? What are its industrial uses?
The first industrial use of cryogenics was the production of liquid air, a primary source of liquid oxygen and liquid nitrogen. Certain aircrafts and spacecrafts carry liquid oxygen that can be converted into gaseous form for crews to breathe during long flights. Other uses of liquid oxygen include the manufacture of synthetic gases and treatment of waste paper. Liquid nitrogen serves as a refrigerant.

4 . What is Super Conductivity?
It is the ability of a material to conduct electricity without any losses to resistance. It is a physical property inherent in a variety of metals and ceramics. It is dependent on temperature, that is, a material will not exhibit superconductivity until the temperature is sufficiently low.

5 . What did Onnes do for getting Nobel Prize?
in 1911, the Dutch scientist Onnes cooled mercury to 4K (-269 degree Celsius). At this temperature, the motion of individual atoms nearly ceased. It was then found that there was no electrical resistance in the material.

6 . What are the major application areas of super conductivity? 50 words 400
Superconducting switching devices that control electronic circuits are used in computers. They operate extremely quickly and produce almost no heat. Power lines made of superconducting materials can transmit electricity over long distances without any loss of power from electrical resistance. Superconductors can be used to make electro-magnets that generate large magnetic fields with no energy loss. This could be used for magnetic suspension of high speed trains or Maglev trains.

7 . What is magnetic levitation? 401
Trains can be made to float on strong superconducting magnets, virtually eliminating the friction between the train and the tracks. Thus greatly reduces the cost of operation. Maglev trains can provide sustained speeds greater than 500kmph, limited only by the cost of power to overcome wind resistance.

8 . What is MRI? 401
Magnetic Resonance Imaging (MRI) is a technique based on the principles of nuclear magnetic resonance. MRI is possible in the human body because the body is filled with small biological magnets, the most abundant and responsive of which is the proton, the nucleus of the hydrogen atom.

9 .  How does  MRI help in medicine? 100 words 401
First, the MRI places the body in a steady magnetic field. Then, the MRI stimulates the body with radio waves to change the steady-state orientation of the protons. It then stops the radio waves and detects the body’s electro-magnetic transmissions at a selected frequency. This transmitted signal is used to construct internal images of the body, using principles similar to those developed for CAT scanners.

It is preferred for diagnosing most diseases of the brain and the central nervous system

10 . How do super conductors help Electric Systems? 402
Electric generators made with superconducting wire are far more efficient than conventional generators wound with copper wire. Power utilities have also begun to use superconducting transformers. An ideal application for superconductors would be to employ them in the transmission of electricity to cities.

11 . What are Petaflop computers? How are they different from teraflop computers? 403
A Petaflop is a 1000-trillion floating point operations per second. NASA is currently researching this. A Teraflop computer has only reached speeds of trillions of operations per second.
12 . What s the. IBM Blue Gene/L computer? 403
Currently the fastest computer is the IBM Blue Gene/L, running at a speed of 280.6 teraflops per second.

13 . What is Josephson junction? 403, 404
Josephson examined the quantum nature of superconductivity and proposed the existence of oscillations in electric current flowing through two superconductors separated by a thin insulating layer in a magnetic or electric field (Josephson junction) although according to classical physics, an electric current cannot flow in a circuit that is interrupted by an insulating barrier. This effect, known as the Josephson Effect, is a feature of quantum electron tunnelling. Thus, it is basically the flow of electric current through non-conductive material.

14 . What are the military uses of super conductors?
Significantly smaller motors are being built for naval ships using superconducting wire. It is also used in degaussing naval vessels. Degaussing of a ship’s hull eliminates residual magnetic fields which might otherwise give away a ship’s presence. Efforts are also being made to use superconducting tape as a means of reducing the length of very low frequency antennas employed on submarines.

15 . What are E Bombs?
A controversial use of superconductors may come with the deployment of E-bombs. These are devices that make us of strong, superconductor-derived magnetic fields to create a fast, high-intensity electro-magnetic pulse to disable the enemy’s electronic equipment.

16 . What are SQUIDs ? 404
Superconducting Quantum Interfering Devices (SQUIDS) are among the most sensitive devices. It is essentially an ultrasensitive detector of magnetic flux, made up of a superconducting ring interrupted by one or two Josephson junctions. It is capable of detecting magnetic fields of around 2T. It is required to be kept at a temperature of about 4.2K.

17 . What is Magnetoencephalography? 405
What is a Neuromagnetometer?
With Magnetoencephalography (MEG), the body can be probed to certain depths without the need for the strong magnetic fields associated with MRIs. It is a non-invasive method for recording minute magnetic fields emanating from the brain.

The MEG device is known as a Neuromagnetometer. It consists of a helmet-like instrument which is placed around a subject’s head.


18 . How do we distinguish the mother’s heartbeat from the Fortal
heartbeat ? 405
SQUIDS can measure the minute magnetic fields generated by a baby’s heart. It has the ability to distinguish the mother’s heartbeat from the baby’s. This allows early diagnosis of foetal heart conditions, which could be potentially life-saving.

19 . Mention some of the applications of Josephson devices. 406
Josephson devices can be used in magnetic sensors, gradiometers, oscilloscopes, decoders, analog to digital converters, samplers, microwave amplifiers, micro-processors and RAMs.

20 . What is  a Bolometer? What is its use?
It is an instrument used to measure infrared radiation or any other form of radiation energy. They are now primarily used in the detection of heat energy transmitted from distant sources. In astronomy, it is used to measure the heat of the stars.

21. What is a Quiteron? 407
Most integrated circuits today use standard transistors. A replacement presently being studied is called a quiteron. If two superconducting materials are separated by an insulating material, it is possible for electron pairs to pass through this material without any resistance (Josephson junction). Due to this, changes in resistance caused by changes in voltages can take place in a billionth of a second or less. This performs the same function as a transistor but at much higher speeds.

22. Mention a few Magnetic anomaly Detectors. 100 words 407
In the military context, the developments were based on detection of submarines by aircrafts. The large amounts of magnetic materials in a submarine causes a slight focusing of the earth’s magnetic field. The innovations in superconductors allowed the measurements of these variations in field strength. The process by which the magnetic fields are detected involves SQUID magnetometers. HTSC SQUIDS are being used by the U.S navy for detection of mines and submarines.

A major use of superconductors in geology is mapping magnetic fields. Devices called magnetometers help to detect magnetic anomalies or distinguish between geological features that would otherwise be indistinguishable.

In the biomedical field, they can be used for muscle measurements, measurement of amounts of iron in the system and cardiac measurements.

23 . What are the future prospects of Super Conductors?

They are expected to play a dominant role in well-established fields such as MRI and scientific research, it could also help to battle climate change. It has been calculated that the EU could reduce carbon dioxide emissions by 53 million tons if super-conductors are used in power plants. The future role of superconductors will also depend on the advancements in cryogenics. Materials such as gadolinium-silicon-germanium are expected to make possible compact refrigeration units.

Nano Science and Nano Technologies

(Summary of TMH book on Science and Technology for UPSC CSE preparations)

1. Distinguish between NANO Science  and NANO technology
Nanoscience is the study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales, whose properties differ significantly from those at a larger scale.

Nanotechnology is the design, characterisation, production and application of structures, devices and systems by controlling the shape and size at the nanometer scale.

2. What is the size of a Nano meter, the human hair, a blood cell and an atom? 385
One nanometer(nm) is one-billionth of a meter. 1 nm = 10-9 m.

A human hair is approximately 80,000 nm wide, a red blood cell is approximately 7000 nm wide, and atoms are below a nanometer in size.

3. What did Feyman mean when he said that there is plenty of room at the bottom?
By this, Feynman meant that there is immense possibility of manipulating materials at the scale of individual atoms and molecules. It is akin to the whole of the Brittanica Encyclopedia written on the head of a pin.

4. How is Nano technology useful in cells and batteries?
An increase in surface area (per unit mass) will result in an increase in chemical reactivity, making some nano-materials useful as catalysts to improve the efficiency of fuel cells and batteries.

5 . Give examples of Nano  technology  occurring naturally
Milk is a nanoscale celluloid. There are more sophisticated examples such as nano-sized and nano-structured proteins that control a range of biological activities such as flexing muscles, releasing energy and repairing cells. Nano-particles are also naturally created in the process of combustion and food cooking.

6. Distinguish between top down and bottom up technologies on Nano technology.
Top-down techniques involve starting out with a block of material, and etching or milling it down to a desired shape. Bottom-up involves the assembly of smaller sub-units (atoms or molecules) to make a larger structure.

7. Distinguish between Nano technology and Micro technology
1 micrometre (micron) is equal to 1000 nanometres. The application of micro-technology is generally far closer to the market as compared to nano-technology. Micro-technology has been commercially exploited for many years, such as in the production of small, powerful computers.

8. What are carbon Nano tubes?
Carbon nano-tubes (CNTs) were first observed by Sumio Iijima in 1991. They are extended tubes of rolled graphene sheets. They are of 2 types- single-walled (one tube) and multi-walled (several concentric tubes). They have novel physical and chemical properties. They are mechanically very strong and are very good conductors of electricity.

9. What is a fullerene?
In the mid 1980s, a new class of carbon material was discovered called carbon 60 (C60). These are spherical molecules about 1nm in diameter, comprising 60 carbon atoms arranged as 20 hexagons and 12 pentagons, which is the configuration of a football. Some applications of fullerene are production of miniature ball bearings to lubricate surfaces, drug delivery vehicles and in electronic circuits.

10. What are Dendrimers?
Dendrimers are spherical polymeric molecules, formed through a nano-scale hierarchical self-assembly process. There are many types of dendrimers. They are used in conventional applications such as coatings and ink.

They have a range of interesting properties. They can act as nano-scale carrier molecules and as such could be used in drug delivery. Dendrimers can assist environmental clean-up as they can trap metal ions, which could then be filtered out of water through ultra-filtration techniques.

11. Energy is equal to wave length or colour. What does this mean?
Energy is related to wavelength or colour. This means that the optical properties of the particle can be finely tuned depending on its size. Thus, particles can be made to emit or absorb certain wavelengths (colours) by controlling their size.

12. Describe some of the  applications  of Nano technology already in use.
Nano-particles are used in the production of carbon nano-tube based tennis racquets, burn dressings and dental fillings. Nano-sized titanium dioxide and zinc oxide are used in sunscreens, as they absorb and reflect the UV radiation. They are also used in composites, which are materials that combine separate components such that they have the best properties of each component.

Carbon fibers are used in polymers to enhance conductivity. A particular type of nano-composite is where nano-particles are used as fillers in a matrix, such as carbon black which is used as a filler to reinforce car tyres.

13. What are clay particles? What is their use?
Clays containing naturally occurring nano-particles have long been important as construction materials. Clay particles based composites – containing plastics and nano-sized flakes of clay- are used in car bumpers.

14. Describe in hundred words some of the future uses of Nano technology.
In the next five years, nano technology could be used in computer hard-disks, self-cleaning windows, better photovoltaic devices for renewable energy sources, anti-corrosion coatings and non-invasive molecular imaging in medicine.

Over the next 5-15 years, they could be used in semi-conductor lasers for telecommunication, high density data storage, better medical implants and artificially created organs and better sensors for pollutants.


14. What is the danger to human health from Nano technology?
There is evidence that suggests that some of the manufactured nano-particles could be more toxic per unit mass than larger particles of the same chemical. Also, it seems that nano-particles can penetrate cells more readily than larger particles. If nano-particles penetrate the skin, they might facilitate the production of reactive molecules that could lead to cell damage. There is also evidence to suggest that combustible nano-particles might cause an increased risk of explosion because of their increased surface area and potential for enhanced reaction.


15. Describe the social and ethical issues arising out of Nano technology in 100 words
The convergence of nano-technology with information technology could result in increased personal safety and security. It could also be equally used for covert surveillance, or for the collection and distribution of information without adequate consent.

As new forms of surveillance and sensing are developed, further research and expert legal analysis might be necessary to establish whether current regulatory frameworks and institutions can provide appropriate safeguards to individuals and groups in society. Bio-terrorism could get a boost with the fusion of nano-technology with chemistry. Nano-technology could even be used to re-engineer human beings.

16. What is the impact of Nano Technology on warfare 100 words
In the military context, nano-technology holds potential for both defence and offence. They could be used to produce more lethal weapons that are much harder to detect than the weapons that are currently being used. Mind-machine interfaces could enable pilots and soldiers to control high-tech weapons by thought alone. ‘Cognitive feedback helmets’ allow remote monitoring of soldiers’ mental state. Pulse weapons and other nuero disrupters could play havoc with enemy soldiers’ thought processes. New drugs could be produced which could enable soldiers to go without sleep for days, to suppress fear, or to repress psychological inhibitions against killing.

17. Describe India ‘s National Mission on Nano Science and Technology. 150 words.
In 2004, President Kalam organised a meeting of nano-science experts to devise a national mission plan. Its recommendations included spending US$22m each year for the next 5 years on 5 new national facilities specialising in complimentary areas of nano-technology and 10 mini-centres across the country.

The President also called for a dynamic task force to identify important national projects and set deadlines for achieving results in areas such as drug delivery systems for cancer and HIV/AIDS.

It is in this background that the GOI in 2007 approved the launch of a mission on Nano Science & Technology (Nano Mission). The New Millennium Indian Technology Leadership programme is also promoting two public-private collaborative ventures for developing nano-technologies that target drugs to exactly where they are needed in the human body.

A national center for nano-materials has been set up at the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI) in Hyderabad.

18. What are the prospects of Nano Technology in India. 100 words
With the core competence of IITs and Indian R&D institutions in collaboration with international institutions and industries, we can create joint venture organisations for many nano-technology products in water, energy, agriculture, health-care, space and defence. But far greater investment is required for this. The Nano Mision may provide the required financial impetus. With the Government approval for this mission, research in nano-science and technology in India appears to be poised for a renewed take-off.

Nuclear and other weapons of mass Destruction

 Nuclear and other weapons of mass Destruction

(Summary of TMH book on Science and Technology for UPSC CSE preparations)

1 . What are WMDs ? What are their lethal effects? 100 words
They are weapons of mass destruction. They include nuclear, biological and chemical weapons. Nuclear weapons kill by the effects of heat, blast, radiation and radioactive fallout. The attacks on Hiroshima and Nagasaki killed an estimated 200,000 people. Biological and toxin weapons kill by using pathogens to attack cells and organs in human bodies, although they can also be used to target crops and livestock on a massive scale.

Some are contagious and spread rapidly, while others like anthrax and ricin infect and kill only those who are directly exposed. Toxins are poisons produced by biological organisms. Some like the botulinum toxin are lethal even in microscopic amounts.

Chemical weapons kill by attacking the nervous system and lungs, or by interfering with the body’s ability to absorb oxygen. Persistent agents can remain in a target environment for over a week.

2 .When and where we’re the first nuclear weapons used?
The first nuclear weapons were used by the Americans on Hiroshima and Nagasaki in august 1945. One was named Little Boy

3 . What is the  Basic Fission Weapon design?
In fission weapons, a mass of fissile material (enriched uranium or plutonium) is assembled into a supercritical mass (the amount of material needed to start an exponential nuclear chain reaction) either by shooting one piece of subcritical material into another, or by compressing a subcritical mass with chemical explosives, at which point neutrons are injected and the reaction begins.

4. What are Fusion Bombs?
They are also known as H-bombs. They utilize the Teller-Ulam design, in which a fission bomb is detonated in a specially manufactured compartment adjacent to a fusion fuel. The gamma and X-rays of the fission reaction compress and heat a capsule of tritium, deuterium, or lithium dueteride starting a fusion reaction.

5. Name the main methods of Detonation of Atomic Bombs.
The main methods of detonation of atomic bombs are gun method and implosion method.

6 . What s the Implosion technique?
This method is utilized in a spherically shaped weapon. The outer part of the sphere consists of a layer of closely fitted and specially shaped lenses, which are composed of high explosives (HE) and designed to concentrate the blast towards the centre of the bomb. Each section of the explosive is equipped with a detonator, which in turn is wired to all other segments. An electrical impulse explodes all the chunks of high explosive simultaneously, resulting in a detonation wave that converges towards the core of the weapon.

7. What are Fissile Materials?
The basis of a nuclear weapon is U-235 or Pu-239. The acquisition of fissile material in sufficient quantity is the most formidable obstacle in the production of nuclear weapons. The minimum mass of fissile material that can sustain a nuclear chain reaction is called a critical mass. The critical mass of the compressed fissile material deceases as the inverse square of the density achieved. Since critical mass decreases rapidly as density increases, the implosion technique can make do with less nuclear material than the gun-assembly method.

8. What are Uranium Isotopes? What is enriching Uranium?
The fissile U-235 isotope accounts for only 0.7% of natural uranium; the remainder is composed of the heavier isotope U-238. Huge gaseous –diffusion plants are used to separate the two. The gas is pumped through barriers that have millions of tiny holes, through which the lighter molecules, which contain U-235 atoms pass by diffusion at a slightly greater rate than the heavier molecules, which contain U-238. After passing through thousands of barriers, the gas is highly enriched in the lighter isotope: U-235.

9. What is Plutonium? How is it produced? 499
U-238 can be converted into fissile material by bombardment with neutrons. This transforms it into a new species of element. U-238 captures a neutron to become U-239, which undergoes disintegration to form neprunium-239 or plutonium-239. Pu-239, like U-235 undergoes fission after the absorption of a neutron and can be used as bomb material.

10. What are non-strategic nuclear weapons?
In general, non-strategic nuclear weapons refers to weapons with a tactical role in the battlefield and that are not intended for use against an enemy’s nuclear missiles or population centres. They include short range nuclear missiles, artillery shells and nuclear mines.

11. What are Thermonuclear weapons?
Thermo-nuclear or fusion weapons involve the fusing together of the nuclei of isotopes of light atoms such as hydrogen. Of the 3 isotopes of hydrogen, the 2 heaviest, deuterium and tritium combine most readily to form helium.

12. What is a Neutron Bomb?
The enhanced radiation fusion bomb, also called the neutron bomb, does not release long lasting radioactive fission products. However, the larger number of neutrons released in thermo-nuclear reactions is known to induce radioactivity in materials, within a relatively small area around the explosion. Thus, it can be used as a tactical weapon as it can do serious damage to tanks and armored vehicles, without producing radioactive fallout over a larger area.

13 . What are Dirty Bombs?
Nuclear terrorists may seek to make radiological weapons or dirty bombs. Using radioactive substances, stolen from research labs or hospitals, they could simply detonate a conventional explosive surrounded by such material, or release it directly as a gas or powder.
14 . Describe the Blast effects of Nuclear Weapons. 502
The very rapid expansion of the bomb materials produces a high pressure pulse, or shock wave, that moves rapidly outward from the exploding bomb. In air, this shock wave is known as the blast wave because it is equivalent to and is accompanied by powerful winds of much greater than hurricane force. The damage radius increases with the power of the bomb approximately in proportion with its cube root.

15 . What are the Thermal effects of Nuclear Weapons?
The very high temperatures attained in a nuclear explosion result in a formation of a fireball. A flash of thermal radiation is emitted from the fireball and spreads out over a larger area, but with steadily decreasing intensity. The thermal radiation falling on exposed skin will cause flash burns.

16 . What is penetrating radiation?
Besides heat and blat, a nuclear bomb also releases penetrating nuclear radiation or nuclear fall out. The nuclear fall out spreads far beyond the area immediately attacked and causes immense havoc. People affected by it develop radiation sickness. Nuclear radiation consists of two types: prompt radiation which affects the people in whose area te bomb explosion takes place. They are affected by burns. This spread over several square kms. There is another radiation which tavels far and wide and affect people. Radio activity continues over the bomb debris and remains for many years.

17.  What is the Atoms for Peace Programme? Describe the work done at BARC in this connection
Under the Atoms for Peace programme, India acquired a Cirus 40MWt heavy water-moderated research reactor from Canada and purchased from the U.S the heavy water required for its operation.

The implosion system or peaceful nuclear explosion used in the ‘Smiling Buddha’ was designed to compress the core to twice its normal density. The lenses that were developed used an RDX-TNT mixture as the fast explosive, with barato9l (barium nitrate and TNT) used as the slow explosive. Most of this work was done at BARC.

18 . Describe the 1998 tests 100 words
India refrained from nuclear testing for 24 years and resumed it in 1998 with a series of nuclear explosions known as Operation Shakti. On May 11 1998, India tested 3 underground devices at Pokhran followed by 2 more tests on May 13, 1998.

Based on seismic data, the U.S estimated the yield of the thermo-nuclear test in the range of 12-25 KT, as opposed to 43-60 KT yield claimed by India. This lower yield caused skepticism about India’s claims to have a detonated a thermo-nuclear device.

The fissile materials used in these tests were completely indigenous. Further, the fabrication of fissile materials to suitable shapes was also performed by BARC. These tests were fully contained with no release of radioactivity in the atmosphere. The tests conducted during May 1998 provided critical data to develop a valuable database for the validation of our capability in the design of nuclear weapons.

19 .What is India’s stand in regard to Nuclear Weapons? 100 words/506

Subsequent to the tests the Government stated that India would henceforth observe a voluntary moratorium and refrain from conducting underground nuclear test explosions. It has also indicated willingness to move towards a de jure formalization of this declaration. The basic obligation of the CTBT was thus met: to refrain from undertaking nuclear test explosions.

India also participated in negotiations on a Fissile Material Cut-off Treaty. The basic objective of this treaty is to prohibit future production of fissile materials for use in nuclear weapons.

India has maintained effective export controls on nuclear materials as well as related technologies even though we are neither a party to the NPT nor a member of the Nuclear Suppliers’ Group. India is committed to non-proliferation and maintaining of stringent export controls to ensure that there is no leakage of our indigenously developed know-how.

India has in the past conveyed its concerns on the inadequacies of the international nuclear non-proliferation regime. It has explained that the country was not in a position to join because the regime did not address our country’s security concerns.

20 .  Why did India resume testing on 1998?
Pakistan is believed to have started its nuclear program soon after India’s peaceful detonation of 1974. India then announced further tests in 1998 and Pakistan followed suit.

21 . Comment on the nuclear capacity of Pakistan in 100  words.  / 507
Pakistan’s nuclear program is based primarily on highly enriched Uranium (HEU). The country’s primary enrichment plant is located at the Dr.A.Q.Khan Research laboratories in Kahuta, while other experimental enrichment sites are at Sihala and Golra Sharif. In addition to producing HEU, Pakistan is attempting to obtain weapons-grade plutonium by extracting it from spent reactor fuel.

The Pakistan institute of Nuclear Science and Technology (PINSTECH) IN Rawalpindi houses Pakistan’s experimental reprocessing plant which can extract 10-20 kg of plutonium per year. Pakistan is also working on a plutonium reprocessing plant near Chashma.

To feed its reprocessing plants, Pakistan has built with clandestine Chinese assistance, a 40MW heavy water reactor at Khushab. This is Pakistan’s only source of plutonium-bearing spent fuel that is not under international safeguards.


22 . What purpose do  enriched uranium, plutonium and  tritium serve? 507
They serve as fissile materials and are required in the production of nuclear bombs.

23 . What is India’s no first use policy? How ha Pakistan responded to it?
India has declared a no first use policy, but not Pakistan. Both support the goal of concluding a multilateral fissile material cut off treaty. Both countries are maintaining a moratorium on nuclear testing, but neither has yet signed the CTBT.

24. Describe in 50 words Pakistan’s clandestine nuclear activities.507
The Pakistan nuclear scientist A.Q.Khan has been at the center of an illicit international supplier network involving both import and export of nuclear technology and equipment. It is believed that Khan originally stole centrifuge designs from Europe and established Pakistan’s uranium enrichment program for bombs. With nuclear assistance to North Korea, Libya and Iran, Pakistan has emerged as the most crucial node for the nexus of terrorism and WMD proliferation.

25 . What. Is PTBT?
The Partial Test Ban Treaty, signed in 1963, banned nuclear tests in the atmosphere, underwater and space. However, neither France nor China, both nuclear weapon states, signed the PTBT.

26 .What is NPT of 1968? Why has India not signed it even while practically adhering to it?
The Nuclear Non-proliferation Treaty (NPT) was signed in 1968. Under this, non-nuclear weapon states were prohibited from possessing, manufacturing or acquiring nuclear weapons. India has not signed the NPT because it felt that the N5 were not prepared to discuss comprehensive nuclear disarmament, but were only looking for ways to protect and safeguard their own nuclear superiority by ensuring that nuclear weapons remained out of reach for most of the world.


27. What is India’s attitude to the CTBT  1996?
According to India, the final text of the CTBT was not a comprehensive ban but merely a ban on nuclear explosive testing. It also lacked a definitive commitment to nuclear disarmament. The kernel of India’s objections is that it divides the world into nuclear haves and have- nots, and places India permanently among the have-nots.

28 . Summarize India ‘s objections to the CTBT 200  words / 509
According to India, the final text of the CTBT was not a comprehensive ban but merely a ban on nuclear explosive testing. It also lacked a definitive commitment to nuclear disarmament. The kernel of India’s objections is that it divides the world into nuclear haves and have- nots, and places India permanently among the have-nots.

India has drawn a distinction between 3 issues—horizontal and vertical proliferation, and disarmament. Horizontal proliferation refers to the spread of existing nuclear technology to new or threshold countries such as India, Pakistan and Israel. Vertical proliferation refers to upgrading and further development of more sophisticated weaponry by the existing nuclear powers. Disarmament, refers to the dismantling of existing nuclear weapons by the 5 nuclear weapon states (N5).

The most significant feature of CTBT is that it essentially addresses only the first goal- horizontal proliferation. India felt that the N5 were not prepared to discuss comprehensive nuclear disarmament but were merely looking for ways to protect and safeguard their own nuclear superiority

29 . What is CTBTO? What have been its objectives and problems ? 510

In order to monitor compliance with the CTBT, a global verification regime is being established. The establishment of the International Monitoring System (IMS) poses engineering challenges unprecedented in the history of arms control, with many stations in remote, inaccessible areas. Over 100 stations are already transmitting data.

The system uses 4 verification methods. Seismic, hydroacoustic, and infrasound stations are employed to monitor the underground, underwater and atmosphere environments respectively. Radionuclide stations can detect radioactive debris from atmospheric explosions or vented by underground or underwater nuclear explosions.

The global verification regime of the CTBT is already partly operational. It has a network of 321 monitoring stations and 16 radionuclide laboratories.

30. What is biological warfare? Summarize in 50 words the weapons of biological warfare.
Biological warfare involves the deliberate cause or spread of disease by biological agents, used as a weapon. Such weapons have the potential to cause immense human harm, panic and societal disruption. These weapons can be divided several ways. One way is to consider the type of agent that causes the disease, such as bacteria, viruses or toxins. Another is to look at the effects, such as a disease that can be transmitted between humans (contagious) or only affects those that are directly exposed to the biological agent.

A third way is to look at the symptoms. For example, some diseases might normally lead to death while others might incapacitate their victims or lead to changes in behavior.

31 . What is the Geneva Protocol on Biological warfare?
It is a protocol (agreement) for the prohibition of the use of asphyxiating gas and bacteriological methods of warfare. It was signed in 1925 and entered into force in 1928. It also commits the parties to exert every effort to induce other states to accede.

32 . What are Chemical weapons? Name some of the main types. 100 words/ 512
Chemical weapons refers to the use of ‘poison’ in warfare. The main types of chemical weapons are – nerve agent : highly lethal, kills in very small dosages, like sarin ,soman.

Blistering agent: causes acid burns and blisters on the body, damages eyes. If inhaled, it severely damages the lungs, which often results in death, like mustard sulphurous gas, lewisite.

Asphyxiating agent: causes damage to the lungs, like phosgene, mustard gas.

Psychotomimetic agent: causes a hallucinatory effect similar in kind to that of LSD, like BZ.

Incapacitating agent: relies on irritant and toxic effects to incapacitate a person temporarily, like tear gas.

Possible new agents: research on new ways of affecting the human brain to cause aggressiveness, sleepiness, fear or other emotions. (bio-regulators).

33.  Briefly explain the classification of chemical weapo s under the Chemical Weapons Convention.
Schedule 1 chemicals include those that have been or can easily be used as chemical weapons and which have very limited, if any, uses for peaceful purposes. These chemicals are subject to very stringent restrictions.

Schedule2 chemicals include those that are precursors to, or in some cases can themselves be used as, chemical weapon agents, but which have a number of other commercial uses such as ingredients in pesticides.

34 . What means of delivery are adopted as WMD?
The first nuclear weapons were delivered by heavy, long range bombers. As nuclear weapons became smaller and lighter over time, a wider variety of aircraft could deliver them, including unmanned aerial vehicles (UAV). Other deployment options arose with the development of nuclear land mines, depth charges, artillery shells and air defense systems.

Both biological and chemical agents can be delivered via aerosols into the air or directly into a water supply. Even fleas, ticks and rodents are possible means for disseminating highly infectious biological agents, as demonstrated by Japan during the second world war.

35 . What are Missile technologies? 50  words
The greatest focus of WMD delivery systems has been on ballistic and cruise missiles , because of their capabilities to deliver such weapons over considerable distances, with increasing accuracy, with little warning and without risk to the pilots. Because of the difficulty of achieving accurate missile flight paths, most long range ballistic missiles that have been developed outside the technically advanced states are not considered suitable for the delivery of conventional warheads.

Missiles encompass a range of types, from ground, sea and air. There are cruise and ballistic missiles and they are often dual-use.

36. Classify Ballistic Missiles
Short range ballistic missiles (SRBM): range less than 1000 km.

Medium range ballistic missile (MRBM): range between 1000 and 2500 km.

Intermediate range ballistic missile (IRBM): range between 2500 and 5000 km.

Intercontinental ballistic missile (ICBM): range over 5000 km.

Submarine-launched ballistic missile: these are distinguished not on the basis of range but of the launch platform being a submarine. This imposes stringent requirements for missile design.

37. What are Cruise missiles? Do they have an advantage?
Cruise missiles refers to unmanned self-propelled guided vehicle that sustains flight through aerodynamic lift for most of its flight path and whose primary mission is to place a special payload on a target.

Cruise missiles, or UAVs, may be more attractive than ballistic missiles owing to their lower cost, ease of acquisition, and better accuracy and reliability.

38. Mention some of the Cruise Missiles. What is India ‘s position regarding them?
The term cruise missiles covers several vehicles , from the Chinese Silkworm (HY-2), which has a range of less than 105 km, to the U.S Advanced Cruise Missile(ACM), which has a range of up to 3000 km. the most well known of the cruise missiles is the US Tomahawk used widely in Afghanistan and Iraq.

Around 40 states are known to have acquired or developed ballistic missiles, but most have only short range delivery capability. Fewer than a dozen states possess medium range missiles. In addition to the 5 nuclear armed NPT states, India, Israel, Pakistan, and North Korea also have such capabilities.

39. Explain in 100 words  missile defences 515-516

While proponents of missile ‘shields’ highlight the specific threats of WMD-capable missiles, there are inherent risks that construction of such systems could provoke a destabilizing offence-defense spiral with regard to missiles, missile defense and outer space. Today, when states are seriously concerned about global terrorist threats, the expenditure of vast resources on missile defense has also been widely criticized as a waste of money, since terrorists have many ways of deploying WMD other than by missiles.

Ballistic missile defense systems are designed to detect attacking missiles; to track missiles; to discriminate between warheads and decoys; and to destroy attacking missiles. Since its withdrawal from the ABM (Anti-ballistic missile) treaty in 2002, the U.S.A has launched its National Missile Defense (NMD) program. The objective of the NMD program is to develop and maintain the option to deploy a cost effective, operationally effective, that will protect the U.S against limited ballistic missile threats.

40. Describe the ABM systems 517
An anti-ballistic missile (ABM) is a missile designed to counter ballistic missiles particularly long range, nuclear armed ICBMs. Only 2 ABM systems have previously been operational against ICBMs, the U.S safeguard system and the Russian A-35 anti-ballistic missile system. 3 shorter range tactical ABM systems are currently operational—the U.S Patriot, Navy Aegis Combat System and the Israeli Arrow.

41 . What are the three types of weapons  for use from space? 517
They are the space strike weapons, anti-satellite weapons (ASAT) and Ballistic missile defense (BMD) weapons.

42 . What are the WMD- related dangers from outer space? 518
The development of weapons designed to attack military satellites, which are used to monitor missile launches and compliance with arms control and disarmament treaties, poses grave dangers to international peace and security. The acquisition by one state of such weapons would inspire others to follow suit, leading to a new arms race.

43 . What is the current status of the outer space security regime? 518

The stationing of nuclear weapons or any other WMD in outer space or placement of such weapons in orbit are both prohibited under the 1967 Outer Space Treaty (OST), but nuclear warheads or BMD interceptors launched from territorial bases are not prohibited, nor is the sub-orbital transit of outer space by nuclear warheads on ballistic missiles.

Science Questions Index

Science Questions & Answers 1

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  • Briefly describe the technological achievements of the Indus people.
  • Outline Ancient India’s achievements in the Sciences.
  • Outline modern India’s contributions to Science
  • What are the principal aims of India’s nuclear energy programmes? Briefly outline her achievements.
  • Examine the role of the DAE in the development of nuclear technology.
  • What has been achieved in regard to Safety and Environment Concerns
  • Explain the progress made in Research and Development in nuclear energy.
  • Examine the progress made in regard to the development of Indigenous Technology
  • What has been the role of the ECIL in the development of the nuclear power programme.
  • Explain the Spin-off Technologies from the nuclear power programme.
  • What has been the achievement of India in regard to nuclear fuel cycle activities
  • What have been achievements in the field of Agriculture?
  • Explain the contributions of nuclear energy in regard to Water Management
  • What is the relevance of electronics to development?
  • Describe the activities of the DOE.

Science Questions & Answers 2

  • Write a note on Earth quake
  • Which is the hardest substance known?
  • From which substance are dyes manufactured?
  • A dynamite cartridge struck in a rock makes the rock burst on being fired. How does it happen?
  • From what was Uranium isolated?
  • What is the difference between hard and soft coal?
  • What is the safety curtain in cinema or theatre made off?
  • Distinguish between flannel and flannelette?
  • Why does a pansy flower turn its face towards the sun?
  • How does a flowering plant feed itself?
  • Why do the plant or animal bodies decay?
  • What do you know about the creatures which are in between plants and animals?
  • What plants are not green?
  • Which creatures live for ever?
  • How do the plants and the animals differ?
  • Why do the animals depend upon the green plants for their food?
  • Are large plants able to move at all?
  • What is the most poisonous animal?
  • Are all snakes harmful?
  • Why are technical words used for describing plants and animal species?
  • Why do plants need sunlight to make their food?
  • Do the plants breathe in Oxygen?
  • Do ants have a sense of smell?
  • Why a whale does come to the surface of the ocean for breathing?
  • How can a worm live, when it is cut into twos?
  • How do leguminous crops improve the nature of soil?
  • Why are a large number of worms seen after a rain storm?
  • Why should one not sleep under a tree at night?
  • Why has a tree so many leaves?
  • Why do flower pots have holes in the bottom?
  • Science & Technology 3
  • ————————————————–
  • Which epidemic diseases often occur in India?
  • What preventive measures should be taken for Malaria, Influenza, Cholera?
  • What are the causes and cure of:
  • What is tuberculosis? How can it be prevented?
  • What are the causes, cure and preventive measures of
  • What is the difference between anti-septics, deodorants and disinfectants?
  • What do you know about protective foods?
  • Why is milk an ideal food for babies?
  • Why is sunlight good for our babies.
  • Why does a heavy stone not break a glass place when placed slowly on it, while a small stone falling from a great height easily breaks it?
  • Why is it more difficult to stop a cricket ball than a tennis ball moving with the same velocity?
  • When we press our hand on a table downwards, why we do feel the table pressing our hand?
  • When a gun is fired, why does the gunner receive the jerk?
  • While swimming, why do we press the water backward with our arms and hands?
  • Why does a boat rise higher, when it passes from river water to sea water?
  • Why is it easier to swim in sea water than in river water?
  • Why does a body weigh more at the poles than at the equator?
  • If a body is hung from a spring balance first at the poles and then at the equator, why do the readings of the balance change?
  • Why does a stone fall when thrown upward, while a balloon rises
  • Why does a boat-man push the bank with an oar, when he wants to clear his boat off the bank?
  • Why is it easy to turn over a leaf with a wet finger?
  • How can a bird fly, while a man cannot?
  • When a toy balloon is filled with air and then the air is allowed to go out, why does the balloon whiz away?
  • When we jump from the boat to the bank why does the boat go backwards from the Bank?
  • Why do we lean forward while climbing up a hill?
  • Dust is removed from a carpet, if we strike it with a stick, why?
  • A rope-dancer holds either an umbrella or a bamboostick, while dancing on the rope. Why?
  • Why does a man carrying a load on his back lean forward?
  • How is the Leaning Tower of Pisa standing at its position till now?
  • How is the Leaning Tower of Pisa standing at its position till now?
  • Why does the liquid not come out of the dropper, unless the rubber is pressed?
  • Why do we not feel the enormous weight of the atmosphere above our heads?
  • Why does a cyclist fall forward, if he applies the brakes suddenly?
  • Why does a piece of iron sink in water, while a ship remains floating?
  • Science Q & A 4
  • Why does a body weigh more at the poles than at the equator?
  • If a body is hung from a spring balance first at the poles and then at the equator, why do the readings of the balance change?
  • Why does a stone fall when thrown upward, while a balloon rises?
  • Why does a boat-man push the bank with an oar, when he wants to clear his boat off the bank?
  • Why is it easy to turn over a leaf with a wet finger?
  • How can a bird fly, while a man cannot?
  • When a toy balloon is filled with air and then the air is allowed to go out, why does the balloon whiz away?
  • When we jump from the boat to the bank why does the boat go backwards from the Bank?
  • Why do we lean forward while climbing up a hill?
  • Dust is removed from a carpet, if we strike it with a stick, why?
  • A rope-dancer holds either an umbrella or a bamboostick, while dancing on the rope. Why?
  • Why does a man carrying a load on his back lean forward?
  • How is the Leaning Tower of Pisa standing at its position till now?
  • Why does the liquid not come out of the dropper, unless the rubber is pressed?
  • Why do we not feel the enormous weight of the atmosphere above our heads?
  • Why does a cyclist fall forward, if he applies the brakes suddenly?
  • Why does a piece of iron sink in water, while a ship remains floating?
  • Science Q & A 5
  • How does the towel dry our hands?
  • Why does bluing make things whiter?
  • Why does starch stiffen the clothes?
  • Why are morning and evening less warm than noons?
  • Why are summers hotter than winters?
  • Why are the mountains colder than the plains?
  • Why does a tennis ball bounce higher in Simla than it does in Calcutta?
  • How will you make the clock go fast?
  • Why do the front wheels of a motor car usually lean outwards?
  • Why does fountain pen filler draw up ink?
  • How is soda in a glass sucked up with the help of a straw.
  • Why does railway carriage in motion not leave the rails?
  • If a number of planes are taking off from an aircraft carrier, what is the minimum interval required between the take-off the successive planes?
  • Why is a flywheel used in motor cars?
  • Why is a jet of water curved on coming out of a horizontal nozzel?
  • Why does a thick glass tumbler break, when ice is put in it?
  • Why are the steam pipes and hot water pipes used for heating rooms, not fixed to the walls firmly at both ends?
  • Why are the girders on the railway bridges fixed at one end only?
  • Why does a piece of ice make drink colder?
  • Why are cloudy usually warmer than clear ones?
  • Why are days and nights equal at the Equator throughout the year?
  • Why are the telegraph wires kept a little loose?
  • Why is one’s breath visible in cold, but not in hot weather?
  • Why is water kept in ` earthen pots’ in summer?
  • A burn from steam is more painful than that from boiling water. Why?
  • Why is ice wrapped in gunny bags?

———————————————-

  • Science Q & A 6
  • ———————————
  • How does fanning produce a sense of coolness on the face?
  • Why does in cold countries, water at the surface freezes while the inner portion it is in the state of water.
  • When a string is placed on a slab of ice, the string passes through it. Why?
  • Why is ice-cream colder to the teeth than cold iced water?
  • Why is a newly made quilt warmer than an old one?
  • What causes smoke to curl up into the air?
  • Why does a dog hang out his tongue, when it is hot?
  • Why does thermos flask keep a hot liquid hot and a cold liquid cold?
  • Why does oil thrown on rough sea make it calmer?
  • Why is heat more oppressive on a damp hot day?
  • Why is dew formed more readily on clear nights than on cloudy ones?
  • If the topper of a bottle has stuck, sometimes it may be removed by heating the neck, why?
  • Why does the snow on the mountains not melt at once, but changes into water very slowly?
  • Why does the water in tanks and ponds not freeze in winter?
  • Why do metallic tools used by blacksmiths have wooden handles?
  • Why do clothes dry quicker in wind than in still air?
  • Why is clinical thermometer used in preference to an ordinary Fahrenheit thermometer?
  • When we pour ice into a tumbler bubbles are seen outside, why?
  • Why do woolen clothes keep us warm in winter?
  • Why does the water boil below 100 degree centigrade on the top of a mountain?
  • Why can’t the meat and dal (pulses) be cooked well on the top of high mountains?
  • When we heat one end of an iron bar, the other end also gets heated up. why?
  • The heat of the sun reaches us and the intervening air is not heated up. Why?
  • Why is a vessel of water heated more quickly, when heat is applied at the bottom than it is heated at the top?
  • Why is the bottom of a kettle blackened and top polished?
  • Science Q & A 7
  • Types of Cropping Patterns and Practices
  • What is deliquescence?
  • What is the basic principle of an internal combustion engine?
  • Why are we able to hear short wave broadcasts better than long wave broadcasts
  • What is the basic characteristic of antigens?
  • Why are detergents superior to the traditional soaps?
  • Stripes on the back of some animals are the indication of-
  • Why is there no twilight on the moon?
  • Why does the air over an oven appear to be quivering?
  • Bacteria was first seen, described and sketched by-
  • In tissue typing, comparison between the child and the father is made on-
  • How does it happen that Pluto is not the farthest planet of the solar system now?
  • Watson-Crick model is a model relating to-
  • What is paraffin oil?
  • What is meant by `Occultation’ of a star?
  • What is radiolysis?
  • What is the main use of Pepsin?
  • What is the main function of centrifuge?
  • Why is water mixed with alcohol applied to the forehead of a person having high fever.
  • The phenomenon of rise or depression of liquid surface in narrow tube is known as-
  • The rate of change of angle of a rigid body rotating about an axis is known as-
  • Why does a body weigh slightly more at the poles than at the equator?
  • What is Easter?
  • What are Lysosomes?
  • What is Golgi apparatus?
  • What is hydroponics?
  • What is egestion?
  • The endocrinal glands are-
  • What are Gymnosperms and Angiosperms?
  • What is a-sexual reproduction?
  • What is pollination?
  • What causes the elongation of stems of genetically dwarf plants?
  • What is a sextant?
  • ————————————
  • Science Q & A 8
  • ———————————
  • Why are gases more easily squeezed than liquids ?
  • Why does water wet glass but mercury does not ?
  • Brownian motion offers strong evidence in support of the … theory
  • A steel needle can be made to float on water due to …
  • Oil rises in a wick due to …
  • Milk is a ….. emuls
  • ion
  • Fog may be called an …
  • Chemical action of an element is dependent on the electrons — True/False
  • If chemical bonding takes place by the transfer of electrons, it is called … bonding
  • Name a device that changes (a) electrical energy to light (b) sound to electrical energy (c) potential energy to kinetic energy (d) electrical energy to kinetic energy
  • What is the amount of work done by someone holding a stone ?
  • What is the S.I. unit of work ?
  • A pendulum bob’s kinetic energy is zero when
  • A girl in pointed heels is likely to do more damage to a wooden floor than an elephant is likely to do. (True/False)
  • Walnuts can be broken in the hand by squeezing two together but not one. Why ?
  • An increase in pressure accompanies …….. in speed.
  • When you blow over a paper sheet it tends to rise. This is explained by ……. Principle.
  • An object sinks in a liquid of (smaller/greater) density than its own.
  • A ship entering a river from the sea would (risk/sink).
  • Science Q & A 9
  • ———————————
  • A stone thrown into a pond creates ripples. These waves
  • In the case of longitudinal waves, the wavelength is the distance between …….
  • A lamp filament that is white-hot, i.e. above 100°C, radiates
  • Which type of electromagnetic radiation is used in the remote control of a television receiver ?
  • An object is sent to burst in the sky and the bang is heard 10 seconds later. If the speed of sound is 330 m/s, how far away is the exploding object ?
  • In a 110 m race, the time-keeper stands near the, finishing line and starts his stopwatch on hearing the bang from the starting pistol. When should he have started his stopwatch and why ?
  • A girl stands 160 m away from a high wall and claps her hands at a steady rate so that each clap coincides with the echo of the one before. If she makes 60 claps in 1 minute, what is the speed of sound ?
  • We can hear sound round the corner of a door. This is an example of ……
  • Sound can be heard sometimes for great distances over water surfaces. This is because sound is ……
  • If a balloon is rubbed, it sticks to the wall at the place where it has been rubbed. Explain.
  • Before replacing a fuse, what is the precaution to be taken ?
  • Why is tungsten used as the filament in a lamp ?
  • If air was used to fill the bulb the tungsten wire …..
  • How much electrical energy (in J) does a 100 W lamp change in 5 seconds ?
  • If a piece of metal was thought to be a magnet, conclusive evidence would be offered of its magnetism only if ……
  • The cell’s shape is usually related to its …..
  • Cell walls are found only in ……. cells.
  • Which part of the cell is called “the power house” ?
  • The “suicide bags” of a cell are the ……
  • Which organelle is considered the centre of protein production ?
  • Which type of cell division plays an important role in regeneration of damaged parts of a living organism ?
  • New genetic variation takes place due to the cell division
  • The chromosomes number is reduced to half during …..

Uranium Centrifuge

What’s a uranium centrifuge?

Uranium is an element that is similar to iron. Like iron, you dig uranium ore out of the ground and then process it to extract the pure uranium from the ore. When you finish processing uranium ore, what you have is uranium oxide. Uranium oxide contains two types (or isotopes) of uranium: U-235 and U-238. U-235 is what you need if you want to make a bomb or fuel a nuclear power plant. But the uranium oxide from the mine is about 99 percent U-238. So you need to somehow separate the U-235 from the U-238 and increase the amount of U-235. The process of concentrating the U-235 is called enrichment, and centrifuges are a central part of the process.

U-235 weighs slightly less than U-238. By exploiting this weight difference, you can separate the U-235 and the U-238. The first step is to react the uranium with hydrofluoric acid, an extremely powerful acid. After several steps, you create the gas uranium hexafluoride.

Now that the uranium is in a gaseous form, it is easier to work with. You can put the gas into acentrifuge and spin it up. The centrifuge creates a force thousands of times more powerful than the force of gravity. Because the U-238 atoms are slightly heavier than the U-235 atoms, they tend to move out toward the walls of the centrifuge. The U-235 atoms tend to stay more toward the center of the centrifuge.

Although it is only a slight difference in concentrations, when you extract the gas from the center of the centrifuge, it has slightly more U-235 than it did before. You place this slightly concentrated gas in another centrifuge and do the same thing. If you do this thousands of times, you can create a gas that is highly enriched in U-235. At a uranium enrichment plant, thousands of centrifuges are chained together in long cascades.

At the end of a long chain of centrifuges, you have uranium hexafluoride gas containing a high concentration of U-235 atoms.

The creation of the centrifuges is a huge technological challenge. The centrifuges must spin very quickly — in the range of 100,000 rpm. To spin this fast, the centrifuges must have:

  • very light, yet strong, rotors
  • well-balanced rotors
  • high-speed bearings, usually magnetic to reduce friction

Meeting all three of these requirements has been out of reach for most countries. The recent development of inexpensive, high-precision computer-controlled machining equipment has made things somewhat easier. This is why more countries are learning to enrich uranium in recent years.

Now you need to turn the uranium hexafluoride gas back into uranium metal. You do this by adding calcium. The calcium reacts with the fluoride to create a salt, and the pure uranium metal is left behind. With this highly concentrated U-235 metal, you can either make a nuclear bomb or power a nuclear reactor

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