Question

Two black bodies A and B have equal surface areas and are maintained at temperatures 27?C and 177?C respectively. What will be the ratio of the thermal energy radiated per second by A to that by B?

• A. 4:09
• B. 2:03
• C. 0.722916667
• D. 1.247916667

Answer 1

Answer: (C)

0.722916667

Answer 2

$Q=\sigma AT^{4}, \frac{Q_{1}}{Q_{2}} =\left(\frac{T_{1}}{T_{2}}\right)^{4} =\left(\frac{273+27}{273+177}\right)^{4} =\left(\frac{300}{450}\right)^{4} =\left(\frac{2}{3}\right)^{4} =\frac{16}{81}$