A black body of surface area $10cm^2$ is heated to $127°C$ and is suspended in a room at temperature $27°C$ . The initial rate of loss of heat from the body at the room temperature will be ...... $W$
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(d) Loss of heat $\Delta Q = A\varepsilon \sigma ({T^4} - T_0^4)t$
==> Rate of loss of heat $\frac{{\Delta Q}}{t} = A\varepsilon \sigma ({T^4} - T_0^4)$
$ = 10 \times {10^{ - 4}} \times 1 \times 5.67 \times {10^{ - 8}}{\{ 273 + 127)^4} - {(273 + 27)^4}\} $
$= 0.99 W.$
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