Question

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

Options

• Kajal

• Blackboard

• A pinhole in a box

• lamp-black

Answer 1

A pinhole in a box

Explanation:

The light that strikes a pinhole enters the box and experiences many reflections on the inner wall. Energy is absorbed with each reflection to some extent. As a result, once the ray enters the box, it cannot exit, and the pinhole behaves exactly like a black body.