Assume that a 100W electric bulb loses its energy entirely by radiation from the surface of its filament . If the surface area of the filament is ` 2 cm^(2)` and its coefficient of emission is 0.4 , calculate the temperature of the filament.

Explanation

` P = 100 W `
p = dQ/ dt = ` e A simga T^(4)`
` T^(4) = P /(e A simga) = 100/ (0.4 xx 2xx 10^(-4) xx 5.67 xx 10^(-8))`
The temperature of the filament
` T = (100/(0.4 xx 2 xx 10^(-4) xx 5.67 x 10^(-8)))^(1//4) = ((100 xx10^(12))/(0.8 xx 5.67))^(1//4)`
`= (22.05)^(1//4) xx 10^(3) = 2167 K`