A light ray passes from air into a block of glass and out th

A light ray passes from air into a block of glass and out the other side into air again. What is its speed after it emerges from the block back into air again? speed is same as that in glass speed is same as that before it entered glass None of the above speed is less than before it entered glass speed is less than before it entered glass speed is less than when in glass

Solution

correct option is B (speed is same as that before it entered glass)
as the speed of light depends on only one variable term which is refractive index.