# Thermodynamics Test

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16
8
4
2
Star A has radius r surface temperature T while star B has radius 4r and surface temperature. The ratio of the power of two starts, PA : PB is ____.
16 : 1
1 : 16
1 : 1
1 : 4
Suppose the sun expands so that its radius becomes 100 times its present radius and its surface temperature becomes half of its present value. The total energy emitted by it then will increase by a factor of ____.
104
625
256
16
If the temperature of the sun were to be increased from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on the earth to what it was previously is?
4
16
32
64
At 127o C radiates energy is 2.7 ( 10-3 J/s. At what temperature radiated energy is 4.32 ( 10 6 J/s?
400 K
4000 K
80000 K
40000 K
If the initial temperatures of metallic sphere and disc, of the same mass, radius and nature are equal, then the ratio of their rate of cooling in same environment is ____.
1 : 4
4 : 1
1 : 2
2 : 1
A black body radiates energy at the rate of 1 ( 105 J / s (m2 at temperature of 227o C. The temperature to which it must be heated so that it radiates energy at rate of 1 ( 109J/sm2 is ____.
5000 K
5000 oC
500 K
500 oC
The temperature of the body is increased from –73 o C to 327 o C; the ratio of energy emitted per second is ____.
1 : 3
1 : 81
1: 27
1 : 9
Two spherical black bodies of radii  and  and with surface temperature and  respectively radiate the same power. Then the ratio of  and  is ____.
Temperature of a black body increases from, the initial energy possessed is 2 KJ, what is its final energy?
32 KJ
320 KJ
1200 KJ
None of the above
The original temperature of a black body is The temperature at which this black body must be raised so as to double the total radiant energy, is ____.
971 K
1190 K
2001 K
1458 K
Two black metallic spheres of radius 4m, at 2000 K and 1m at 4000 K will have ratio of energy radiation as ____.
1 : 1
4 : 1
1 : 4
2 : 1
The energy spectrum of a black body exhibits a maximum around a wavelength. The temperature of the black body is now changed such that the energy is maximum around a wavelength .The power radiated by the black body will now increase by a factor of ____.
A black body is at a temperature 300 K. It emits energy at a rate, which is proportional to ____.
The spectral energy distribution of star is maximum at twice temperature as that of sun. The total energy radiated by star is ____.
twice as that of the sun
same as that of the sun
sixteen times as that of the sun
one sixteenth of sun
Hot water cools from  to  in the first 10 minutes and to 42° in the next 10 minutes. The temperature of the surrounding is ____.
Consider two hot bodies  and  which have temperatures  and  respectively at . The temperature of the surroundings is . The ratio of the respective rates of cooling  and  of these two bodies at  is ____.
Newton's law of cooling is a special case of ____.
Stefan's law
Kirchhoff's law
Wein’s law
Planck's law
Equal masses of two liquids are filled in two similar calorimeters. The rates of cooling will ____.
depend on the nature of the liquids
depend on the specific heats of liquids
be same for both the liquids
depend on the mass of the liquids
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This is Thermodynamic test of Physics

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