Question

A black body is an ideal system that. a) absorbs \(100 \%\) of the light incident upon it, but cannot emit light of its own. b) radiates \(100 \%\) of the power it generates, but cannot absorb radiation of its own c) either absorbs \(100 \%\) of the light incident upon it, or radiates \(100 \%\) of the power it generates. d) absorbs \(50 \%\) of the light incident upon it, and emits \(50 \%\) of the radiation it generates. e) blackens completely any body that comes in contact with it.

Short answer

Answer: A black body either absorbs 100% of the light incident upon it, or radiates 100% of the power it generates.

Step-by-step solution

Eliminate incorrect options

We can start by eliminating the options that do not describe the behavior of a black body: a) A black body does absorb all incident light, but it can also emit light (in the form of black body radiation), so this option is incorrect. b) A black body does radiate all the power it generates, but it also absorbs radiation, so this option is incorrect. e) Black body has nothing to do with blackening other bodies, so this option is incorrect. Now we have two remaining options: c) either absorbs 100% of the light incident upon it, or radiates 100% of the power it generates. d) absorbs 50% of the light incident upon it, and emits 50% of the radiation it generates.

Identify the correct statement

We know that a black body perfectly absorbs all wavelengths of energy incident upon it, which means it absorbs 100% of the light incident. It also emits 100% of the power it generates in the form of black body radiation. This matches the description given in option (c). So, the correct statement is: c) A black body either absorbs 100% of the light incident upon it, or radiates 100% of the power it generates.