Question

The temperature of perfect black body is $ 727{}^\circ C $ and its area is $ 0.1\,{{m}^{2}} $ . If Stefans constant is $ 5.67\text{ }watt/{{m}^{2}}s{{K}^{-4}}, $ then heat radiated by it in 1 minute is:

• A. 8100 cal
• B. 81000 cal
• C. 810 cal
• D. 81 cal

Answer 1

Answer: (B)

$ Q=A\sigma t{{T}^{4}} $ $ =\frac{0.1\times 5.67\times {{10}^{-8}}\times 60\times {{(1000)}^{4}}}{4.2}\text{cal} $ $ =81000\,cal $