Question

Two bodies $A$ and $B$ are placed in an evacuated vessel maintained at a temperature of $27^{\circ} C$. The temperature of $A$ is $327^{\circ} C$ and that of $B$ is $227^{\circ} C$. The ratio of heat loss from $A$ and $B$ is about

• A. 2 : 1
• B. 1 : 2
• C. 4 : 1
• D. 1 : 4

Answer 1

Answer: (A)

For body A rate of heat loss is
$E _{ A }=\sigma A \left(600^{4}-300^{4}\right)$
For body $B$ rate of heat loss is
$E_{B}=\sigma A\left(500^{4}-300^{4}\right)$
So ratio of heat loss is
$E_{A} / E_{B}=\left(600^{4}-300^{4}\right) /\left(500^{4}-300^{4}\right)$
$=2.23: 1 \approx 2: 1$