Question

A black body at a temperature of $227 ^ { \circ } \mathrm { C }$ radiates heat energy at the rate of 5 cal/cm²-sec. At a temperature of , the rate of heat radiated per unit area in cal/cm²will be

• A. 80
• B. 160
• C. 250
• D. 500

Answer 1

Answer: (A)

80

Answer 2

$\frac { E _ { 2 } } { E _ { 1 } } = \left( \frac { T _ { 2 } } { T _ { 1 } } \right) ^ { 4 }$ $= \left( \frac { 273 + 727 } { 237 + 227 } \right) = \frac { ( 1000 ) ^ { 4 } } { ( 500 ) ^ { 4 } } = 16 \Rightarrow E _ { 2 } = 80$