Question

when light wave suffersreflection at the interface from air to glass , the change in phase of the reflected wave is equal to

Answer 1

Crests are reflected as troughs and troughs are reflected as crests when the light is reflected off a denser medium with a higher index of refraction. The wave is said to undergo an 1800 reflective phase change. The net effect of the change in phase is that the reflected ray'' springs ahead' by half a wave length.

Phase changes by π (pie) when reflecting from a denser medium and phase change is zero for reflecting from a rarer medium. Phase change is also zero during refraction.

Answer 2

When light is reflected off a more dense medium with higher index of refraction, crests get reflected as troughs and troughs get reflected as crests. The wave is said undergo a 180 change of phase on reflection. The net effect of the phase change is that the reflected ray ``jumps ahead" by half a wave length.