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
For a gas, the difference between two principal specific heats is 4150 J kg-1 K-1 . What is the specific heat of the gas at constant volume if the ratio of specific heats is 1.4 ?
5186 J kg-1 K-1
10375 J kg-1 K-1
1060 J kg-1 K-1
8475 J kg-1 K-1
A body cools from 60°C to 50°C in 10min. If room temperature is 25°C , the temperature of the body at the end of next 10 min will be
38.5°C
42.8°C
40°C
45°C
A thermometer has wrong calibration. It reads the melting point of ice as - 10o C, the temperature of boiling point of water on this scale is :
-20o C
-40o C
-10o C
-10.7o C
According to Newton's law of cooling, the rate of cooling of a body is proportional to , where is the difference of the temperature of the body and the surroundings and n is equal to
Two
Three
Four
One
A black body has maximum wavelength λm at 2000 K. Its corresponding wavelength at 3000 K will be
A sphere is at a temperature of 600K. Its cooling rate is R' in an external environment of 200 K. If temperature falls to 400 K, then cooling rate R' will be
3R/16
16R/3
9R/27
none of these
The unit of Stefan's constant :
Wm-2K-1
WmK-4
Wm-2K-4
Nm-2K-4
The earth receives at its surface radiation from the sun at the rate of 1,400 Wm-2. The distance of the centre of the sun from the surface of the earthy is 1.5 x 1011 m and the radius of the sun is 70 x 108 m. Treating sun as a black body, it follows from the above data that its surface temperature is:
5,801 K
106 K
50.1 K
5,801oC
Heat current is maximum in which of the following (rods are of identical dimension) ?
