The graph shown in the adjacent diagram, represents the variation of temperature (T) of two bodies X and Y having the same surface area, with time (t) due to the emission of radiation. Find the correct relation between the emissivity and absorptivity power of the two bodies ?
eX < eY and aX > aY
eX > eY and aX > aY
eX < eY and aX < aY
Let 50 g of ice at 0oC is mixed with 50 g of water at 80oC, final temperature of mixture of will be:
0oC
40oC
60oC
4oC
Two spheres of the same material have radii 1 m and 4 m and temperatures 4,000 K and 2,000 K respectively. The ratio of the energy radiated per second by the first sphere to that by the second is:
1 : 1
1 : 9
4 : 1
16 :1
The unit of Stefan's constant is :
Wm-2K-1
WmK-4
Wm-2K-4
Nm-2K-4
One end of a thermally insulated rod is kept at a temperature T1 and the other at T2. The rod is composed to two sections of lengths L1 and L2 and the coefficients of thermal conductivity K1 and K2respectively. The temperature at the interface of the two sections is:
If the temperature of the sun is doubled, the rate of energy received on earth will be increased by a factor of
2
4
8
16
540 g of ice at 0o C is mixed with 540 g of water at 80o C. The final temperature of the mixture is
40o C
79.9o C
80o C
0o C
In determining the temperature of a distant star, one makes use of:
Kirchhoff's law
Stefan's law
Wien's displacement law
Millman's theorem
The intensity of radiation emitted by the sun has its maximum value at a wavelength of 510 nm and that emitted by the North Star has the maximum value at 350 nm. If these stars behave like black bodies, then the ratio of the surface temperature of the sun and the North Star is:
1.46
0.69
1.21
0.83
Which of the following processes depends on gravity ?
Conduction
Convection
Radiation
Diffraction