Question

Given that $p$ Joules of heat is incident on a body and out of it $q$ Joules is reflected and transmitted by it, the absorption coefficient of the body is

• A. $(q-p)/p$
• B. $q/p$
• C. $(p-q)/p$
• D. $p/q$

Answer 1

Answer: (C)

$(p-q)/p$

Coefficient of absorption is defined as the ration of amount of radiation a body absorbs to the amount of radiation that is incident on the body.
Incident radiation = $p$
Rejected radiation = $q$
Hence absorbed radiation must be = $p-q$
From the definition of absorptive power it follows that the power = $\frac{p-q}{p}$