Usually, a smallhole on the wall ofan enclosure painted in black from inside is given as an example for blackbody.The argument given is that any radiation that falls on the hole goes inside. This radiation has little chance to come out of the hole again and it gets absorbed by multiple reflections.The cone directly opp. to the hole ensures that the incoming radiation is not directly reflected back to the hole.....
Hrishant Goswami , 10 Years ago
Grade 10