Question

Calculate the energy radiated per minute from the filament of an incandascent lamp at 2000k if the surface area is 5 m2 and its relative emittance is 0.85

Answer 1

Answer:The energy radiated per minute is $E =  3876\times10^{3}\ J$ .

Explanation:

Given that,

Temperature T = 2000 K

Surface area $A = 5 m^{2}$

Relative emittance $e = 0.85$

Using Stefan's law of radiation

The total heat energy emitted from a surface is proportional to the fourth power of temperature.

The energy radiated is

$E = e\sigma T^{4}A$

Where, $\sigma$ = Stefan's constant

$E = 0.85\times 5.7\times10^{-8}\times(2000)^{4}\ K\times5\ m^{2}$

$E = 3876\times10^{3}\ J$

Hence, the energy radiated per minute is $E = 3876\times10^{3}\ J$.