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In the following few pages of this book, questions on Fundamentals of Sciences are given.   A perusal of these will help you face the Interview with confidence.   Also revise brief points relating to your subject.  (Physics/Chemistry/Biology/Zoology  etc.)

Q. Mention the outstanding work of each of the following persons:
(i) Charles Darwin; (ii) Alexander Flemings; (iii) Madame Curie; (iv) Alfred Nobel; (v) Louis Pasteur.

A. (i) Charles Darwin: He was a British biologist who discovered the theory of evolution.
(ii) Alexander Fleming: He was a Scottish bacteriologist who discovered penicillin in 1928.
(iii) Madame Curie: She was a French physicist who isolated radium.
(iv) Alfred Nobel: He was a Swedish scientist who invented dynamite.
(v) Louis Pasteur: He was a French chemist who discovered vaccination for hydrophobia and gave Germ Theory of Diseases.

Q. Who invented pneumatic tyre.
A. John Boyd Dunlop (1840-1921).

Q. For what important scientific works are the following famous?
(i) Sir Frederick Grant Banting; (ii) Hideki Yukawa; (iii) Edward Jenner; (iv) Sir James Young Simpson; (v) C.V. Raman.

A. (i) He discovered hormone insulin which is used in the treatment of diabetes. Sir Banting received Nobel Prize in 1923.
(ii) He discovered a group of elementary particles called MESONS. The weight of meson is intermediate between that of an electron and a proton. Received Nobel Prize in 1949.
(iii) He discovered vaccination for small pox.
(iv) He worked on chloroform (CHCl3).
(v) He studied the phenomenon in light known after his name ‘Raman Effect’. Received Nobel Prize in 1930.


Q. How does a submarine float and sink as desired?
A. The submarine has a chamber in which water can be filled in or pumped out as required. To make it sink into the water, the chamber is filled with water so that its weight exceeds the upthrust produced on the submarine by the displaced water. To bring the submarine up, the water in the chamber is pumped out. Now the upthrust produced by the displaced water is greater than or equal to the weight of submarine and hence it can float.

Q. Why is cooking quicker in a pressure cooker?
A. The boiling point of water (or any other liquid) depends upon the pressure on its surface. Steam produced inside the cooker builds up pressure thereby raising the boiling point of water, which results in quick cooking.

Q. Why does an electric bulb make a ‘bang’ when it is broken?
A. There is a vacuum inside the electric bulb. When the bulb is broken air rushes in at great speed from all sides to fill the vacuum. The rushing of air produces a noise generally referred to as a ‘bang’.

Q. Why are curved railway tracks banked?
A. The outer part of a railway track near the bend or a curve is generally raised, i.e., the outer track of the bend is slightly higher than the inner. This is known as banking of the rails or tracks. When a fast moving train takes a curved path, it tends to move away tangentially off the track. In order to prevent this, the curved tracks are banked on the outside to produce the necessary centripetal force required to keep the train moving in a curved path. If there is no banking of the track, this centripetal force that is obtained from the friction between the rim of the wheels and rails which is generally small may cause the train to jump off the rails.

Q. Why can’t a petrol fire be extinguished by pouring water over it?
A. Water, being heavier, slips down and petrol will rise to the surface and continue to burn as before. Hence, water cannot be used for extinguishing petrol fire.

Q. Why do a gram of weight and a pound of weight released simultaneously from the top of a tower reach the ground at the same time?
A. This is in accordance with the fact that both the weights fall with the same acceleration of 9.8 metres/sec2. Since they are released simultaneously they will travel equal distance in equal time and, therefore, reach the ground at one and the same time.

Q. What would happen if the force of gravity were to disappear suddenly?
A. In the absence of the force of gravity all living objects on the earth will be practically in a floating condition. They will be thrown away because of the centrifugal force caused by the rotation of earth. Thus, one will not be able to eat, drink, move and continue to live.

Q. Why does a needle sink in water while an iron ship floats on it?
A. According to the law of floatation, a body floats in a liquid when the weight of the whole body is equal to the weight of the liquid displaced by the immersed portion of the body. A needle or solid steel ball sinks in water because the weight of water displaced by it is less than the weight of needle or steel ball. An iron ship is so shaped that it can displace a large volume of water. The weight of the water displaced by the immersed portion of the ship is equal to the ship. Hence, it can float.

Q. When a moving train slows down quickly, will a passenger tend to fall backward or forward? Explain why?
A. The passenger will tend to fall forward because the lower portion of his body which is in contact with the seat will come to rest quickly whereas the upper portion of the body continues to be in a state of motion. Hence, the person is thrown forward.

Q. Explain why it takes more time to cook meat and vegetables at hill stations?
A. The boiling point of water depends upon the pressure on its surface. It increases with increase of pressure and decreases on lowering of pressure. At higher altitudes the atmospheric pressure is low as compared to that in the plains and, therefore, water boils below 100oC. Hence, sufficient heat is not supplied for cooking the meat and vegetables at hill stations. This difficulty may be overcome by using a pressure cooker. Water can be made to boil at any desired temperature with the help of this appliance.

Q. Why is it more difficult to breathe on mountains than on plains?
A. With higher altitudes the pressure of air goes on decreasing. The oxygen content in the air is also reduced considerably. We experience difficulty in breathing on mountains because the pressure of air outside is less as compared to the pressure of air inside the lungs.

Q. Why does ink leak out of a partially filed pen when taken to a higher altitude?
A. The density as well as pressure of air goes on decreasing with altitude. When a partially filled pen is taken to a higher altitude, it leaks because the pressure of air acting on the ink inside the pen is greater than the pressure of air outside.

Q. Explain why one leans forward while climbing a hill?
A. The person leans forward in order to keep himself in stable equilibrium. By leaning forward he increases the base of the support, so that the vertical line passing through his centre of gravity may fall within the base. For similar reasons, a man has to bend backward while climbing down a hill.

Q. Why is it dangerous to allow extra passenger on the upper deck of a double-decker bus?
Explain why passengers in a boat are not allowed to stand?
A. This is done so that the centre of gravity of the bus is not raised and the bus may not topple over due to unstable equilibrium. For the similar reason, passengers in a boat are not permitted to stand.

Q. Why is a small space left at the joint between the two rails?
A. Metals expand on heating and contract on cooling. A small space is left between each set of two rails of railway line to allow for their expansion in summer and contraction in winter, respectively.

Q. If a highly corked glass bottle full of water is left outdoors on a frosty night it will burst. Why?
A. The water contained in the bottle will freeze on a frosty night and convert into ice. There occurs an increase in volume during this transformation. As there is no room available for the increased volume, this may result in bursting of the bottle.

Q. When we drink soft drink through a straw, why does the liquid go up into our mouth?
A. When a person sucks air from the straw, the pressure of air inside the straw is reduced as compared to the atmospheric pressure acting on the surface of the liquid. Therefore, the soft drink rushes up into the straw and to the mouth.

Q. What weight of air do we carry?
A. 14.72 pounds per square inch.


Q. Explain why the moisture gathers on the outside of a glass tumbler containing cold water?
A. Because the water vapour present in air get cooled and appear as droplets of water on coming in contact with the cold surface of the glass tumbler.

Q. Explain why in winter evenings and morning fog or mist tends to collect in valleys?
A. Because in winter evenings and mornings the temperature of the atmosphere is sufficiently low so as to cause the condensation of water vapour present in the atmosphere. The condensed water vapour being heavy, appear as fog or mist and tend to collect in valleys.

Q. Explain why it snows on high hills, while it rains lower down?
A. The temperature of the atmosphere at higher altitudes in generally below the freezing point of water. Hence, the water vapour present in the air at higher altitudes get converted into snow which collects on the hills. Lower down, the temperature of the atmosphere is above the freezing point of water. Hence, the water vapour is  not converted into liquid water which comes down as rain in those regions.

Q. Explain why—if you are sweating, you will feel cooler on a hot day than on a cooler moist day?
A. On a hot dry day the perspiration gets evaporated quickly causing more cooling effect. On a cooler moist day the rate of evaporation is comparatively less. Therefore, the cooling caused by evaporation is also less on a cooler moist day. Hence, after sweating one feels cooler on a hot day than on a cooler moist day.

Q. Explain why—if a highly pumped up bicycle tyre is exposed to heat it may burst?
A. All gases expand on heating. When a highly pumped up bicycle tyre is left in the hot, there occurs considerable increase in the volume of the air. As sufficient space for the expansion of the air is not available (because bicycle tyre is already highly pumped), it may result in bursting of the tyre.

Q. Why does a thermometer kept in boiling water show no change of temperature even when the water is continuously heated?
A. A liquid boils at a particular temperature called the boiling point of the liquid. Once the liquid starts boiling the thermometer reading remains constant because there is o further increase in temperature. The quantity of heat supplied is being utilized as latent heat in converting the liquid at boiling point into vapour at the same temperature. That is why a thermometer kept in boiling water shows no change of temperature even when the water is continuously heated.

Q. Why do pipes carrying water often burst in cold countries during winter?
A. The temperature falls below 0oC in severe cold resulting in the conversion of water to ice. Since there occurs an increase in volume during this transformation, it exerts a great force which results in the bursting of water pipes.

Q. Why does water get cooled on evaporation?
A. Some heat energy is utilized during the process of evaporation. This energy is taken from the water itself thus producing a lowering of temperature in the remaining water. Hence, water gets cooled on evaporation.

Q. Explain why water gets cooled in an earthen pot much more than in a metal or glass container?
A. In an earthen pot, water gets evaporated through the pores of the pot quickly. As explained in the previous question cooling is caused by evaporation. In the case of metal or glass container, there are no pores with the result that the rate of evaporation is quite low, thus producing only a slight fall in temperature.

Q. Why does the ice not readily melt when salt is sprinkled over it?
A. When salt is sprinkled over ice, some of it dissolves, As dissolution of the salt is accompanied by absorption of heat, the temperature of the system will fall below 0oC. Hence, ice, does not melt readily.

Q. Why will a while roof keep your house cooler in summer than will a black roof?
A. White roof will reflect more and absorb less heat rays whereas black roof will absorb more and reflect less heat rays. Hence, a white roof will keep the house cooler in summer.

Q. Why is it hotter on a cloudy night than in a clear night?
A. Because clouds prevent the heat radiated out by the earth from escaping into the sky. As this heat remains in the atmosphere, the cloudy nights are warmer in comparison to clear nights.

Q. Why are cloudy days cooler but cloudy nights warmer than the clear ones?
A. Because clouds do not allow the sun rays to fall on earth. Moreover, clouds can absorb more heat radiation as compared to dry air. Both these factors prevent the earth from becoming too much heated. Hence, cloudy days are comparatively cooler. (Also see previous question.)

Q. Why are metal tyres of cart wheels fitted when hot?
A. Metal (iron) tyre is heated strongly. On heating tyre expands and the circumference of the tyre becomes slightly bigger than the wooden wheel. This permits the easy slipping of the tyre on wooden wheel. Thereafter, cold water is poured over the metal tyre and it shrinks in size. Therefore, its circumference fits the wheel well and holds on tightly.

Q. Explain how dew is formed?
A. The objects on the surface of the earth receive direct heat rays from the sun during day time and get heated up. During night, objects lose heat by radiation and their temperature falls. Those objects which are good radiators of heat radiate heat more quickly and get cooled below the temperature of the surroundings. Air, on coming in contact with these cooled objects, in turn, loses its heat and becomes saturated with the vapour it contains. If the temperature of air is reduced to its dew point, the water vapour present in it condenses to form dew which collects on the surface of the cold bodies. Dew is generally formed on green plants, leaves and grass as they are good radiators of heat.

Q. Why do we perspire before rains?
A. Just before the rain falls the atmosphere gets saturated with water vapours. The perspiration exuded by us, therefore, does not evaporate quickly but appears on the surface of the skin. Hence, we feel the perspiration at that time.

Q. Why is Eau-de-cologne applied to the forehead of a sick person?
A. Eau-de-cologne, which is volatile in nature, will evaporate as soon as it is applied on the forehead of a sick person. During the process of evaporation, some heat from the body will be taken away which results in lowering the temperature of the sick person. Thus eau-de-cologne helps to bring down the body temperature and provides relief to the sick person.

Q. Why is the water in an open pond cool even on a burning hot day?
A. This is due to the fact that cooling is caused by evaporation. As the water evaporates from the surface of tank or pond, a good deal of heat is taken away. This results in lowering the temperature of remaining water.

Q. Why does a perspiring man feel relief when air floats by his side?
A. The flow of air increases the rate of evaporation of perspiration from the body. During the process of evaporation, some body heat is taken away thus giving a sense of coolness to the body and providing relief to the perspiring person.

Q. Account for the following: By putting on a shirt, a person feels warm.
A. Cloth is poor conductor of heat. It, therefore, prevents the body heat to escape in winter. During summer external heat cannot reach the body for the same reasons. Hence, a person wearing a shirt feels comfortable.

Q. How does the thermos keep the liquid hot for long time?
A. It is a flask in which loss or gain of heat through conduction, convection and radiation has been reduced to a minimum. It is used for keeping a hot liquid hot and a cold liquid cold for a good length of time.

Q. Why is water from a hand pump warm in winter and cold in summer?
A. In winter outside temperature is low as compared to the temperature of water obtained from the hand pump. Hence, it feels warm. This is due to the fact that the upper layer of the earth’s crust is exposed to the atmosphere and is at a lower temperature. Water, which is underground, is comparatively at a higher temperature. In summer the outside temperature is high and, hence, the water from a hand pump feels cold.

Q. A thick glass tumbler often cracks when a very hot liquid is poured in it. Why?
A. The inner surface of the thick glass tumbler coming in contact with the hot liquid expands more in comparison to the outer surface which is relatively at a lower temperature. The uneven expansion of inner and outer surface may produce cracks.

Q. Glass when heated cracks, while metal does not. Explain.
A. Glass is a poor conductor of heat. On heating, the heat is not transmitted quickly. This results in unequal expansion of the inner and outer surface of glass which may crack. On the other hand, metal is a good conductor of heat. Therefore, when heated, the heat is transmitted quickly and uniformly in all directions. The expansion produced is uniform and, therefore, cracking cannot take place.

Q. Ice wrapped in a blanket does not melt away quickly. Why?
A. Woollen blanket is a bad conductor of heat. It does not allow the external heat rays to enter. Therefore, ice does not melt for a considerable length of time.

Q. Why are places near the sea cooler in summer and warmer in winter than the hinterland?
A. Because of its high specific heat it takes longer for water to get heated up or to get cooled. During summer days the land near the sea gets heated up quickly but the sea water remains cool and thus cool breeze blowing from the sea reduces the heat in the adjoining land area. The reverse happens in winter. The land gets cooled quickly but the sea water remains warm and thus the land gets warm breeze from the sea. But the land farther inside does not have this advantage. This accounts for the difference in the climatic conditions.

Q. Why does grass gather more dew in the night than stones and bricks?
A. Dew is easily formed on the objects which are good radiators, bad conductors and are in close contact with the surface of the earth. Grass and leaves are better radiators of heat than stones and bricks. Hence, more dew is formed on grass and leaves. Moreover, grass and leaves give out water constantly which appears in the form of dew because the air near them is saturated with water vapours.

Q. Why are mornings and evenings less warm than noon?
A. In the mornings and evenings the rays of the sun falling on earth are slanting and their distance is more. The earth gets heated up only slightly. At noon the rays of the sun falling on earth are nearly vertical and the distance is also less, with the result that the earth gets heated up considerably. Hence, mornings and evenings are less warm than noon.

Q. Why do we perspire on a hot day?
A. Human body is physiologically conditioned to maintain uniform temperature. When the heat produced in the body becomes excessive and not dissipated properly, the sweat glands inside the body are stimulated to secrete sweat. Therefore, we perspire on a hot day. However, when sweat evaporates from the body it produces a cooling effect.

Q. Why does a housewife blacken the bottom of the ‘degchi’ used in the kitchen?
A. The blackened surface absorbs more heat as compared to polished surface. That is why blackened ‘degchi’ is used.

Q. Steam causes a severer burn than boiling water. Why?
A. The amount of heat possessed by steam (100oC) is much greater than the amount of heat possessed by water at the same temperature. This is due to the fact that to convert 1 gm of water at 100oC into steam (100oC), 540 calories of heat are required. This additional heat contained in steam is responsible for causing severe burns.


Q. What causes an object to look black?
A. The colour of an object depends upon the nature of light falling on it and also on the constituent colour of the incident light reflected or transmitted by it. If all the constituent colours of the incident light are absorbed by the body, it appears black.

Q. Why is rose red and grass green in day light?
A. A rose appears red when day light falls on it because it absorbs all the constituent colours of white light except red which it reflects to us. Similarly, grass absorbs all the constituent colours of white light except green which is reflected to us. Therefore, grass appears green to us.

Q. What will be the colour of grass in blue light?
A. Grass will appear dark in colour in blue light because it has property of absorbing all other colours except its own colour. The blue rays falling on grass are absorbed by it and, therefore, it appears dark in colour.

Q. The colour of the same cloth when seen in electric light appears different from the colour when seen in daylight. Why?
A. When a body is viewed in daylight, it reflects some colour which is called its natural colour. Electric light, on the other hand, is not pure. It may be deficient in some colours or has got some particular colour in excess. This is the reason why objects sometimes appear to be of a different colour in artificial light from their natural colour which they give in the white light.

Q. A dark blue suit appears black when viewed in candle light. Why?
A. Candle light is deficient in blue colour whereas yellow colour is in excess. When yellow light falls on the blue suit, blue colour is absorbed by it and, therefore, the appearance of the suit is black.

Q. Why does a green leaf appear green in day light but dark in red light?
A. A green leaf appears green in day light because it absorbs all the constituent colours of white light except green which is reflected to us. Green leaf appears dark when viewed in red light because it has the property of absorbing all colours except green. As red rays falling on the leaf are absorbed by it, it will appear dark.

Q. Why does a coil lying at the bottom of a can filled with water look at lesser distance below the water level than it actually is?
Why does a swimming pool appear less deep than it really is?
A. This is due to the phenomenon of refraction of light. The rays of light coming from the bottom of the pool (or from the coil lying at the bottom of the can) travel from water to air. As the rays pass from denser (water) to rarer (air) medium they bend away from the normal. When the rays are produced back they form an image of the coil (bottom of the pool) at a point which is a little above the real position. Therefore, the coil appears to be slightly raised and the pool appears to be less deep than it really is.

Q. Why when a gun is fired within a visible distance, the sound is heard a little after the smoke is seen?
A. The velocity of light is much greater than that of the sound. In other worlds, light travels faster than sound. Therefore, the flash of lightning or smoke of the gun is seen before the thunder of lightning or the sound of the gun being fired.

Q. In summer, white or light coloured clothes are preferred to dark coloured clothes. Why?
A. White or light coloured clothes are good refractors and bad absorbers of heat whereas dark-coloured clothes are good absorbers of heat. Therefore, in summer, white or light-coloured clothes are preferred because they absorb very little heat from the sun’s rays and reflect more. Hence, the person feels more comfortable.

Q. Why is a rainbow seen after rain?
A. After the rain some clouds continue to linger in the sky and they contain water droplets. Water droplets act like prisms. Sun’s rays falling on water droplets suffer dispersion and produce a spectrum. The different colours are viewed in the form of a rainbow.

Q. Although each eye perceives a separate image, we do not see everything double. Why?
A. The axes of the two eyes are directed towards the same object. Therefore, there appears to be only one object. The two separate images formed by two eyes get fused in the brain. The optic nerves lead to the same pointing the brain producing only one sensation. Hence, we see only one object with two eyes. It may be pointed out that we also hear only one sound with two ears.

Q. One eye is sufficient to form the image of an object. What is the advantage of having two eyes?
A. The area seen clearly with one eye is comparatively less (approximate range 135o) than with two eyes (range 180o). Two eyes also give better judgement of distances of different objects.

Left eye sees more of the right side of the object and the right eye more of the left side. Thus, two eyes do not form exactly similar images and the fusion of these two dissimilar images in the brain gives the three dimensional or the stereoscopic vision.

Q. Why is it difficult to thread a needle with only one eye?
A. It is difficult to estimate the relative distance between the thread and the walls of the hold of the needle with one eye. The thread, therefore, passes not through the needle but in front or behind the hole of needle.

With two eyes, however, it is easy to judge the relative distance between two points. Hence, it becomes easy to thread the needle with two eyes.

Q. Why do we bring our hands close to the mouth while shouting to somebody at a distance?
A. By bringing the hands close to our mouth, the sound energy is not allowed to spread in all directions, rather being made unidirectional (i.e., directed in a particular direction). Hence, the sound produced is louder.

Q. Why are fuses provided for electric installations?
A. A safety fuse is a wire made up of a material having a low melting point. It is inserted in an electrical circuit as a safety device not to allow excess current to flow through the circuit. When the current exceeds the limiting value the fuse wire gets heated, melts and breaks the circuit.


The study of science is a quest for knowledge, often as opposed to intuition, belief, etc. It is, in fact, systematized knowledge derived from observation, study and experimentation carried on in order to determine the nature or principles of what is being studied. There are many sciences, each concerned with a particular field of study. In each science, measurement plays an important part. In each science, too, a study is made of the laws according to which objects react. Here are some sciences:

Acoustics: The study of sound (or the science of sound).

Astrology: The ancient art of predicting the course of human destinies with the help of indications deduced from the position and movement of the heavenly bodies.

Biochemistry: The study of chemical processes of living things.

Biology: The study of living things.

Botany: The study of plants.

Chemistry: The study of elements and their laws of combination and behaviour.

Economics: The science dealing with the production, distribution and consumption of goods and services.

Electronics: Studies the development, behaviour and applications of electronic devices and circuits.

Geography: The development of science of the earth’s surface, physical features, climate, population, etc.

Geology: The science that deals with the physical history of the earth.

Horticulture: The cultivation of flowers, fruits, vegetables and ornamental plants.

Hydropathy: The treatment of disease by the internal and external use of water.

Numerology: The study of numbers. The study of the date and year of one’s birth and to determine the influence on one’s future life.

Optics: The study of nature and properties of light.

Ornithology: The study of birds.

Orthopedics: The science of prevention, diagnosis and treatment of diseases and abnormalities of musculoskeletal system.

Pathology: The study of diseases.
Physical Science: The study of natural laws and processes other than those peculiar to living matters, as in physics, chemistry and astronomy.

Radio Astronomy: The study of heavenly bodies by the reception and analysis of the radio frequency electromagnetic radiations which they emit or reflect.

Seismology: The study of earthquakes and the phenomena associated with it.

Sericulture:  The raising of silkworms for the production of raw silk.

Telepathy:  Communication between minds by some means other than sensory perception.

Zoology:  The study of animal life


Ampere:  Unit of electric current. It is approximately equal to the flow of 6x1018 electrons per second.

Atomic Weight: The weight of an atom of hydrogen is taken as the standard; the respective weights of the atoms of all other substances are expressed in terms of it. So when it is stated that the atomic weight of iron is 56, it is meant that the atom of iron is 56 times as heavy as the atom of hydrogen.

Angstrom: The unit of wavelength of light is Angstrom. 1 Angstrom = 10-8 cm. There is a bigger unit for measuring the wavelength of infra-red light; it is called a milli-micron and is equal to 10-7 cm. Micron = 10-4 cm, is a still bigger unit.

Bar is the unit of atmospheric pressure; one bar is equal to a pressure of 106 dynes per sq cm.

Calorie is the unit of heat. It is the amount of heat required to raise the temperature of one gram of water through 1oC.

Horse Power: The practical unit of power—the power of an agent which can work at the rate of 550 foot-pounds per second or 33,000 foot-pounds per minutes. 1 HP = 746 watts.

Joule is the unit of work or energy. It is equal to 107 ergs. It is the energy consumed in one second in an electrical circuit through which a current energy of one ampere is flowing against a potential difference of one volt.

Knot is a measure to know the speed of a ship.

Light Year: A light year is the distance light travels in one mean solar year, at a speed of 1,86,000 miles per second. It is equal to 5,880,000,000,000 miles. It is used as a unit for measuring stellar distances.

Nautical Mile: A unit of distance used in navigation—one minute of longitude measured along the Equator. A Nautical Mile is approximately equal to 6,080 feet.

Pressure: The pressure is expressed in pounds weight per sq cm. The pressure of the atmosphere is expressed in millibars. One millibar = 1 dyne per sq cm. If the pressures are very high, they are expressed in multiples of atmospheric pressure.  I atmosphere is a pressure exerted by a column of mercury 76 cm high at sea level and at a latitude of 45o.

Quintal:  Metric measure of weight; 100 kilograms = 1 quintal.

Volt:  The unit of potential difference.  It is that much potential difference which when applied to the ends of an electrical conductor of resistance one ohm, the amount of energy consumed in the circuit in one second is one Joule (=10 7ergs).

Watt:  Unit of power- the rate of work done in joules per second; the energy expended per second by an unvarying electric current of  1 ampere.


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