At temperature near OK, (zero kelvin) metals such as lead and tin become
insulators
semiconductors
superconductors
condenser
Correct Answer :
C. superconductors
Related Questions
The ballistic missile, Agni 11, tested by India has a maximum range of
1000 km
1500 km
2000 km
500 km
The mirage is a phenomenon
generally considered as a desert happening
caused by unequal heating of the several layers of the atmosphere above the desert
in which the refracted rays take a curved path resulting in total internal refection
All the above
The phenomenon of spontaneous disintegration of certain heavy nuclei is termed
radioactivity
fission
fusion
implosion
A proton is
a quantum of light energy
a quantum of matter
a positively charged atomic particle
another name for positron
A man stands in a lift which accelerates upwards. The resultant reaction force on the floor of the lift is
greater than the weight of the man
less than the weight of the man
same as the weight of the man
zero
Who first established the fact that the earth revolves round the sun?
Sir Isaac Newton
Kepler
Copernicus
Ptolemy
A workman was working on a rail track. A young boy at a distance holds his ear close to the railway track. The boy was able to hear the sound of each blow or the workman twice. It is because
speed of sound is greater in steel than in air
speed of sound is greater in air than in steel
part of sound waves is reflected between rail tracks
the boy's ears are at a different distance from the source
Velocity of sound in high altitudes is low because at such a height
the temperature is low
there is no air
the pressure is low
All the above
Like magnetic poles
attract each other
repel each other
neither attract nor repel
attract or repel depending upon the conditions
The body of an electrical appliance is earthed in order that
electricity may not leak
there may be smooth flow of electricity
a short circuit may be prevented
current may pass to the earth in case of a short circuit without doing any harm to the person
If an empty cylinder Is half ruled with a liquid, Its centre of gravity is
shifted upwards
shifted downwards
shifted neither upward nor downward
shifted upward or downward depending on the density of the liquid
The attraction of unlike molecules at the common surface is known as
adhesion
cohesion
surface tension
capillarity
The overhead wires supported by high towers in the grid system carry
alternating current of very high frequency
alternating current of very high voltage
a very large direct current
a high voltage direct current
A solar eclipse occurs when the earth, the sun and the moon are in a straight line, and
when the moon passes between the sun and the earth
when the sun comes between the earth and the moon
when the earth comes between the sun and the moon
on a full moon day
The coil of an electric heater is made of
Platinum
Tungsten
Nichrome
Copper
The minimum velocity required by a satellite to escape earth's gravitational pull is
18 km/s
11.2 km /s
21 km/s
35 km/s
In the visible spectrum which colour has the shortest wavelength?
Red
Blue
Yellow
Violet
The speed of light is minimum while passing through
air
glass
vacuum
water
The Indian Satellite System used for domestic communications, television and meteorology is known as
INSAT
Bhaskara
Aryabhatta
All the above
The theory that the earth constituted the centre of the universe around which the sun and the planets revolved was propounded by
Copernicus
Ptolemy
Newton
Kepler
Where does the centre of gravity of a rubber ring lie?
on the outer surface
in the inner surface
at the centre of the ring
None of the above
If you want to open a door with les difficulty you push it
at the middle
at a point away from the hinge (near the rim)
near the hinge
None of the above
A stone floor feels cold to the bare feet but a carpet on the same floor feels warm. This is because
the floor and carpet are at different temperatures
the stone conveys the heat away from the feet more rapidly than the carpet
the carpet is a better conductor of heat than the stone
the human body maintains a constant temperature
It is difficult to bon potatoes at the top or a mountain because
the water available is hard
it is colder than at sea level
the potatoes become hard
the boiling point of water is lower at that height on account of low atmospheric pressure
Water kept in an earthen pot is less cool on rainy days than in summer because during the rainy days
the pores in the pot are closed
rain water stops oozing out from the pores
the water that oozes out does not evaporate quickly because of the large percentage of moisture in the air
surface of the pot becomes damp
In experiments on static electricity the standard method for obtaining small amounts of positive electricity is to rub
a glass rod with flannel
an abonite rod with flannel
a glass rod with silk
Any of the above
A hunter on the ground wishes to shoot a bird on a tree at a distance with his rifle. He has to point the rifle
at the lower elevation than the bird
at a higher elevation than the bird
in the same direction as the bird
vertically upwards
The base of an electric iron is brightly polished mainly
to make it smooth and frictionless
to make it rust - proof
to reduce heat loss by radiation
to make it more durable
Nichrome is used in electric heaters and irons because
it resists oxidation when red hot
its melting point is high
it has got 60 times the resistance of copper
All the above
To concentrate light on the defective teeth, the dentists use
convex mirrors
concave mirrors
convex lens
concave lens