Question

A polished metal plate with a rough black spot on it is heated to about $1400\text{K}$ and quickly taken to a dark room. The spot will appear

• A. darker than the plate surface
• B. brighter than the plate surface
• C. equally bright as the plate surface
• D. equally dark as the plate surface

Answer 1

The correct option is B brighter than the plate surface

On heating, the black spot will absorb maximum radiation while the polished part reflects most of the radiation. Therefore, when the plate is taken to a dark room, the spot will emit more radiations than the rest of the plate surface. Hence, it will appear brighter than the plate surface.