Which of the following is an example of ideal black body?

Options

(a) Kajal
(b) Black board
(c) A pin hole in a box
(d) None of these

Correct Answer:

A pin hole in a box

Explanation:

A pin hole in a box is an example of black body. The pin hole allows radiations of different wavelengths to enter the box. Inside box all the radiations are absorbed. No waves are permitted to escape. Hence it acts like an ideal black body.