In a dark room with ambient emperatureT', a black body is kept at a temperature T. Keeping the temperature of the black body constant (at T), sunrays are allowed to fall on the black body through a hole in the roof of the dark room. Assuming that there is no change in the ambient temperature of the room, which of the following statement(s) is/are correct?

 

A. The quantity of radiation absorbed by the black body in unit time will increase.

 

B. Since emissivity=absorptivity, hence the quantity of radiation emitted by the black body in unit time will increase.

 

C. Black body radiates more energy in unit time in the visible spectrum.

 

D. The reflected energy in unit time by the black body remains constant.

 

The answer is A,B,C,D.

This question appeared in the last year JEE paper.

Can someone explain the answer to me?