A light ray in air enters and passes through a block of glass. What can be stated with regard to its speed after it emerges from the block?
A) Speed is less than when in glass.
B) Speed is same as that before it entered glass.
C) Speed is same as that in glass.
D) Speed is less than before it entered glass.

Question

Quizplus · Accepted Answer

When a light ray emerges from a block of glass back into air, its speed returns to the original speed it had before entering the glass, as the speed of light is constant in a given medium and air is the same medium it started in.

A Light Ray in Air Enters and Passes Through a Block