Physics - Heat
Exam Duration: 60 Mins Total Questions : 30
The temperature of boiling water in steam engine may be high because
- (a)
there are dissolved substances in water
- (b)
there is low pressure inside the boiler
- (c)
there is high pressure inside the boiler
- (d)
the fire is at very high temperature
Which of the following is the best conductor of the heat?
- (a)
Mercury
- (b)
Silver
- (c)
Leather
- (d)
Benzene
What is the principle by which a cooling system (Radiator) in a motor car works?
- (a)
Convection
- (b)
Conduction only
- (c)
Radiations only
- (d)
Both conduction and radiation
White clothes are cooler than black ones because they
- (a)
absorb all the light that reaches them
- (b)
reflect all the light that reaches them
- (c)
will not allow the light to penetrate
- (d)
cool the sun light completely
The change of a solid into vapour directly is called
- (a)
vapourization
- (b)
freezing
- (c)
melting
- (d)
sublimation
When water is heated from 0\(^{0}\)C to 10\(^{0}\)C, its volume
- (a)
increases
- (b)
decreases
- (c)
does not change
- (d)
first decreases and then increases
Low temperatures (cryogenics) find application in
- (a)
space travel, surgery and magnetic leviation
- (b)
surgery, magnetic leviation and telemetry
- (c)
space travel, surgery and telemetry
- (d)
space travel, magnetic leviation and telemetry
Which of the following is the example of ideal black body?
- (a)
Black board
- (b)
Kajal
- (c)
A pin hole box
- (d)
None of these
The temperature of water at the bottom of a waterfall is higher than that at the top because
- (a)
water at the bottom has greater potential energy
- (b)
the surface at the bottom provides heat
- (c)
kinetic energy of falling water is converted into heat
- (d)
falling water absorbs heat from the surroundings
Transfer of heat energy from a heater coil to the cooking vessel takes place through the process of
- (a)
convection only
- (b)
conduction and convection only
- (c)
radiation and convection only
- (d)
convection, conduction and radiation
At normal temperature due to a puncture, the compressed air inside the tube of a car wheel suddenly starts coming out. Then the air inside the tube
- (a)
starts becoming hotter
- (b)
starts becoming cooler
- (c)
remains at the same temperature
- (d)
may becomes hotter or cooler depending on the amount of water vapour present in the air
The best conductor of heat among the following is
- (a)
alcohol
- (b)
mercury
- (c)
ether
- (d)
water
The water from a hand-pump is warm in winter because
- (a)
our body is cold in winter and water appears to be warm
- (b)
the temperature inside the earth is higher than the atmospheric temperature
- (c)
the pumping process causes friction which warms up the water
- (d)
inside water comes out and absorbs heat from the environment
In the winter season if we touch two blocks one of iron and another of wood in the early morning then the block of iron appears to be more cold because
- (a)
the temperature of the iron block is less than that of the wooden block
- (b)
iron is a bad conductor of heat in comparison of the wood
- (c)
iron is a bad conductor of heat in comparison of the wood
- (d)
the block of iron is heavier than the wooden block
Consider the following statements
1. Steam at 100\(^{0}\)C and boiling water at 100\(^{0}\)C contain same amount of heat.
2. Latent heat of fusion of ice is equal to the latent heat of vaporization of water.
3. Conditioner heat is extracted from the room air at the evaporator coils and is rejected out at the condenser coils.
Which of these statements is/are correct?
- (a)
1 and 2
- (b)
2 and 3
- (c)
Only 2
- (d)
Only 3
A hollow sphere of radius R, a hollow cube of side R and thin circular plate of radius R made up of the same material, are all heated to 20\(^{0}\) C above room temperature. When left to cool in the room, which of them will reach the room temperature first?
- (a)
Circular plate
- (b)
Cube
- (c)
Sphere
- (d)
All of them will reach the room temperature at the same time
Heat is transmitted from higher to lower temperature through actual mass motion of the molecules in
- (a)
coduction
- (b)
radiation
- (c)
convection
- (d)
All of these
Woollen clothes keep the body warm because
- (a)
wool absorbs radiant heat from outer objects
- (b)
wool increases the temperature of the body
- (c)
wool is the bad conductor of the heat so it does not allow heat to flow out of the body
- (d)
wool rejects heat from outer objects
Consider the following statements
1. Thermal radiation are electro-magnetic waves.
2. Thermal radiations are reflected from mirror.
3. All bodies emit thermal radiations at all temperatures.
4. Thermal radiations of all wavelengths travel in free space with same velocity.
Which of the statements(s) given above are correct?
- (a)
1, 2 and 3
- (b)
1, 3 and 4
- (c)
1, 2, and 4
- (d)
1, 2, 3, and 4
The boiling point of liquid is
- (a)
increases with increase in pressure
- (b)
affected by addition of soluble solid
- (c)
Both (a) and (b)
- (d)
None of the above
Which of the following is the correct device for the detection of thermal radiation?
- (a)
Liquid-in-glass thermometer
- (b)
Constant volume gas thermometer
- (c)
Thermophile
- (d)
None of the above
The product of the pressure and volume of an ideal gas is
- (a)
directly proportional to its temperature
- (b)
inversely proportional to its temperature
- (c)
a constant
- (d)
approximately equal to the universal gas constant
The pressure exerted on the walls of the container by a gas is due to the fact that the gas moleculs
- (a)
stick to the walls
- (b)
lose their kinetic energy
- (c)
change their momenta due to collision with the walls
- (d)
are accelerated towards the walls
Which one of the following would a hydrogen balloon find easiest to lift? The latent heat of vaporization of a substance is always
- (a)
greater than its latent heat of fusion
- (b)
greater than its latent heat of sublimation
- (c)
equal to its latent heat of sublimation
- (d)
less than its latent heat of fusion
A liquids boils when its vapour pressure equals
- (a)
the atmosphere pressure
- (b)
the pressure of 76.0 cm column of mercury
- (c)
the critical pressure
- (d)
the dew point of the surroundings
Dry ice is
- (a)
ice cube
- (b)
sodium chloride
- (c)
liquid nitrogen
- (d)
solid carbon dioxide
Mud houses are cooler in summer and warmer in winter because
- (a)
Mud is superconductor of heat
- (b)
Mud is good conductor of heat
- (c)
Mud is bad conductor of heat
- (d)
None of the above
A body, which emits radiations of all possible wavelengths is known as
- (a)
good conductor
- (b)
partial radiator
- (c)
absorber of photons
- (d)
perfectly black body
When red glass is heated in dark room it will seem?
- (a)
Green
- (b)
Purple
- (c)
Black
- (d)
Yellow
Which among the following materials were used for minting coins during the rule of the Mauryas?
- (a)
Gold and Silver
- (b)
Silver and Copper
- (c)
Copper and Bronze
- (d)
Gold and Copper