BANK INTERVIEW A FEW QUESTIONS ON SCIENCE
SCIENCE AND TECHNOLOGY
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.
EVERYDAY
SCIENCE
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?
Or
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.
HEAT
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.
LIGHT
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?
Or
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.
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BRANCHES OF SCIENCE
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
SCIENTIFIC
MEASURES
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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