The maximum wavelength of radiation emitted by a black body at 1227°C is λm. What is its maximum wavelength at 2227°C?
A black body radiates energy at the rate of E watt m–2 at a temperature of T Kelvin. When the temperature is reduced to T/2 Kelvin, the radiant energy will become |
Answer |
A body at higher temperature T K radiates heat at a rate which is proportional to |
Answer |
According to Prevost’s theory of heat exchange, the heat exchange shops at |
Answer |
The best ideal black body is |
Answer |
The rate of cooling of a body is 0.5°C/minute, when the body is 50°C above the surrounding. What is the rate of cooling if the body is 30°C above the surrounding? |
Answer |
Coefficient of transmission and coefficient of reflection for a given body are 0.22 and 0.74 respectively. Then, at a given temperature, the coefficient of emission for the body is |
Answer |
Wien’s constant units is |
Answer |
A body radiates heat at the rate of 4 cal/m2/s, when its temperature is 227°C. what is the heat radiated by the same body when its temperature is 727°C? |
Answer |
The earth receives at its surface radiation from the sun at the rate of 1400 W/$m^{2}$. The distance of the centre of the sun from the surface of the earth is 1.5 × $10^{11}$ m and the radius of the sun is 7.0 × $10^{8}$ m. Treating sun as a black body, it follows from the above data that its surface temperature is, |
Answer |
Two thermometers A and B exposed to sunlight. The value of A is painted black but that of B is not painted. The correct statement regarding this case is |
Answer |