When `q_(1)` joules of radiation is incident on a body if reflects and transmits total of `q_(2)` joules. Find the emissivity of the body.

Answer

`(q_(1)-q_(2))/(q_(1))`

Explanation

Absorptive power `=(q_(1)-q_(2))/(q_(1)) = (Q_(a))/(Q_(i))`
Emissivity `= (q_(1)-q_(2))/(q_(1))`
Absorptive power = Emissivity