Question

The temperature of a body is increased from $-73^{\circ}\,C$ to $327\,^{\circ}\,C$. Then the ratio of emissive power is

• A. 44570
• B. 44588
• C. 27-Jan
• D. Jan-81

Answer 1

Answer: (D)

Jan-81

Answer 2

Radiation from a body = R
R = e $\sigma T^{4}$ ? time ? area, where e = emissive power
? $\quad eT^{4}$ = constant or e =$\left(\frac{constant}{T^{4}}\right)$
or $\frac{e_{1}}{e_{2}}=\left(\frac{T_{2}}{T_{1}}\right)^{^4}$ or $\frac{e_{1}}{e_{2}}=\left(\frac{273+327}{273-73}\right)^{^4}$
$=\left(\frac{600}{200}\right)^{^4}=\frac{\left(3\right)^{4}}{1}=\frac{81}{1}$
or $\frac{e_{1}}{e_{2}}=\frac{81}{1}$