Question 396: Properties of Matter

Question

Which of the following is best close to an ideal black body?

Accepted Answer

An ideal black body is one which absorbs all the incident radiation without reflecting or transmitting any part of it. Black lamp absorbs approximately 96% of incident radiation.
An ideal black body can be realized in practice by a small hole in the wall of a hollow body (as shown in figure) which is at uniform temperature. Any radiation entering the hollow body through the holes suffers a number of reflections and ultimately gets completely absorbed. This can be facilitated by coating the interior surface with black so that about 96% of the radiation is absorbed at each reflection. The portion of the interior surface opposite to the hole is made conical to avoid the escape of the reflected ray after one reflection.
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Answer

black lamp

Answer

cavity maintained at constant temperature

Answer

platinium black

Answer

a lump of charcoal heated to high temperature.

Properties of Matter

Which of the following is best close to an ideal black body?

Choose the correct answer: