# Thermodynamics: Test of Physics

The amount of radiation emitted by a perfectly black body is proportional to ____.
temperature on ideal gas scale
fourth root of temperature on ideal gas scale
fourth power of temperature on ideal gas scale
source of temperature on ideal gas scale
A metal ball of surface area  and temperature  is surrounded by a vessel at. If the emissivity of the metal is 0.4, then the rate of loss of heat from the ball is  ____.
108 joules approx
168 joules approx
182 joules approx
192 joules approx.
The rate of radiation of a black body at 0°C is. The rate of radiation of this black body at  is ____.
An object is at a temperature of. At what temperature would it radiate energy twice as fast? The temperature of the surroundings may be assumed to be negligible ____.
800 K
A black body at a temperature of  radiates heat energy at the rate of . At a temperature of, the rate of heat radiated per unit area in cal / cm2 is ____.
80
160
200
150
Energy is being emitted from the surface of a black body at  temperature at the rate of . Temperature of the black body at which the rate of energy emission is  is ____.
If temperature of a black body increases from  to , then the rate of energy radiation increases by ____.
16
4
2
The temperature of a piece of iron is  and it is radiating energy at the rate of . If its temperature is raised to , the rate of radiation of energy is come approximately ____.
The temperatures of two bodies A and B are  and. The ratio of rate of emission of radiations is ____.
The temperature at which a black body of unit area loses its energy at the rate of 1 joule/second is ____.
65 K
None of the above
The area of a hole of heat furnace is . It radiates calories of heat per hour. If the emissivity of the furnace is 0.80, then its temperature is ____.
1500 K
2000 K
2500 K
3000 K
Two spheres  and, of same colour having radii  and  are maintained at temperatures  and  respectively. The ratio of energy radiated by  and  is ____.
0.054
0.0034
1
2
A body radiates energy  at a temperature of . If the temperature is increased to, then it radiates energy at the rate of ____.
A thin square steel plate with each side equal to 10 cm is heated by a blacksmith. The rate of radiated energy by the heated plate is 1134 W. The temperature of the hot steel plate is ____. (Stefan's constant, emissivity of the plate = 1)
The temperatures of two bodies  and  are respectively  and. The ratio  of the rates of heat radiated by them is ____.
5 : 3
25 : 9
625 : 81
The energy emitted per second by a black body at  is . If the temperature of the black body is increased to , the energy emitted per second is ____.
The radiant energy from the sun incident normally at the surface of earth is. What would have been the radiant energy incident normally on the earth, if the sun had a temperature twice of the present one?
A spherical black body with a radius of  radiates  power at. If the radius was halved and the temperature doubled, the power radiated in watt would be ____.
225
450
900
1800
If the temperature of the sun (black body) is doubled, the rate of energy received on earth is increased by a factor of ____.
2
4
8
16
The ratio of energy of emitted radiation of a black body at  and  is ____.
1 : 4
1 : 16
1 : 64
1 : 256
Description:

This test is on Heat transmission chapter in Thermodynamics

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ALL THE QUESTIONS ARE OF SAME MODEL TRY TO GIVE DIFFERENT MODELS

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