Question

A black body is heated from $27^{\circ} C$ to $927^{\circ} C$ the ratio of radiations emitted will be :

• A. 0.219444444
• B. 0.086111111
• C. 1:16
• D. 1:04

Answer 1

Answer: (A)

0.219444444

Answer 2

Here : Initial temperature $T_{1}=27^{\circ} C =300\, K$ Final temperature $T_{2}=927^{\circ} C =1200\, K$ According to Stefan's law that the radiant energy is $E \propto T^{4}$ here $\frac{E_{1}}{E_{2}}=\frac{T_{1}^{4}}{T_{2}^{4}}$ $=\left(\frac{300}{1200}\right)^{4}=\left(\frac{1}{4}\right)^{4}$ $=\frac{1}{256}$ Hence, $E_{1}: E_{2}=1: 256$