Question

An ideal black body is thrown into a furnace. The black body is room temperature. It is observed that ___________

(a) Initially, it is darkest body and at later times the brightest

(b) At all times it is the darkest body

(c) It cannot be distinguished at all times

(d) Initially, it is the darkest body and at later it cannot be distinguished

I got this question by my college director while I was bunking the class.

I need to ask this question from Thermal Expansion in section Thermal Properties of Matter of Engineering Physics I

Answer 1

The correct option is (a) Initially, it is darkest body and at later times the brightest

For explanation I would say: Initially at lower temperature, it absorbs the entire radiations incident upon it. So, it is the darkest body. At later times, when it attains the temperature of the furnace, the black body radiates maximum energy. It appears brightest of all bodies.