Question

For a certain body, the coefficient of absorption (absorptive power, absorptivity) is 0.4. The body is maintained at a constant temperature. The radiant power of a perfect blackbody maintained at the same temperature is 5 × 10⁴ W/m² . Find the radiant power of the body at that temperature.

Answer 1

Data: a = 0.4, R_b = 5 × 10⁴ W/m²

As the emissivity, e = a, 

we have, e = 0.4

∴ R = eR_b = (0.4) (5 × 10⁴ W/m²)

= 2 × 10⁴ W/m²

This is the required quantity.