Four identical pieces of copper are painted with different types of paints. Which one would you expect to lose heat most rapidly if they are all heated to be same temperature and allowed to cool in vacuum ?

Options

A. painted rough white
B. painted shining white
C. painted rough black
D. painted shining black.

Answer

C

Explanation

`Eprope(T-T_(0))`
For black body `e=1` and for other bodies `egt1`
`:.` rate of loss of heat is maximum for rod painted black. Thus correct choice is (c ).