Question

Estimate the power loss thriugh unit area from a perfectly black body at 327 degree celsius to the surrounding enviroment at 27degree celsius.

Answer 1

Given :

$T= 327 deg C$ $= 600K$( absolute temperature of black body)

$T_o = 27degC = 300K$(absolute temperature of surroundings)

To find:

Power loss

Solution:

According to Stefan's law of radiation ,we know that , net rate of loss of heat ( power loss ) from a perfectly black body is given by:

Power loss $= A \sigma (T^4-T_o^4)$

It is given that surface area , $A= 1m^2$

$\sigma = 5.67 \times 10^-^8 Jm^-2K^-^4s^-^1$ ( stefan's constant )

Substituting the values , we have :

Power loss $= 5.67\times 10^-^8 \times 10^8 \sqrt{1296-81}$

                   $= 5.67\times 34.85$

                   $= 197.63 J$