Question

A body radiates energy $5 W$ at a temperature of $927 ^ { \circ } \mathrm { C }$, then it radiates energy at the rate of

• A.
• B. 81 W
• C.
• D. 200 W

Answer 1

Answer: (C)

Answer 2

Rate of energy $\frac { Q } { t } = P = A \varepsilon \sigma T ^ { 4 }$

⇒ $P \propto T ^ { 4 }$

⇒ $\frac { P _ { 1 } } { P _ { 2 } } = \left( \frac { T _ { 1 } } { T _ { 2 } } \right) ^ { 4 }$ $= \left( \frac { 927 + 273 } { 127 + 273 } \right) ^ { 4 }$ $\Rightarrow P _ { 1 } = 405 \mathrm {~W}$