Define emissive power and coefficient of emmision of a body.
Emissive power of a body at a given temperature is the quantity of radiant energy emitted by the body per unit time per unit surface area of the body at that temperature.
If ‘Q’ is the amount of radiant energy emitted, ‘A’ is the surface area of the body and ‘t’ is the time for which body radiates energy, then the emissive power is
Coefficient of emission of a body is the ratio of the emissive power of the body at agiven temperature to the emissive power of a perfectly black body at the same temperature.
Coefficient of emission, `e=E/E_b`
The dimensions of emissive power are
(A) [M1 L-2 T-3 ]
(B) [M1 L2 T-3 ]
(C) [M1 L0 T-3 ]
(D) [M1 L0 T-2 ]
The susceptibility of magnesium at 300 K is 2.4 x 10-5. At what temperature will the susceptibility increase to 3.6 x 10-5?
The susceptibility of magnesium at 300K is 1.2 x 10-5. At what temperature will the susceptibility increase to 1.8 X 10-5?
1000 tiny mercury droplets coalesce to form a bigger drop. In this process, temperature of the drop _______ .
(B) may increase or decrease
(D) does not change