Question

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

• A. initially it is the darkest body and at later times the brightest
• B. it is the darkest body at all times
• C. it cannot be distinguished at a times
• D. initially it is the darkest body and at later times it cannot be distinguished

Answer 1

The correct option is A initially it is the darkest body and at later times the brightest

Black body radiates maximum number of wavelength and maximum energy if all other conditions (e.g. temperature surface area etc.) are same. So, when the temperature of back body becomes equal to the temperature of the furnace, the black body will radiate maximum energy and it will be brightest of all. Initially, it will absorb al the radiant energy incident on it, so it is the darkest one.