Question

A wave or a pulse is reflected normally from the surface of a denser medium back into the rare medium .The phase change caused by the reflection-

1)0
2)pi/2
3)pi
4)3pi/2

Answer 1

Light waves change phase by 180° when they reflect from the surface of a medium with higher refractive index than that of the medium in which they are travelling. A light wave travelling in air that is reflected by a glass barrier will undergo a 180° phase change, while light travelling in glass will not undergo a phase change if it is reflected by a boundary with air.