Upon reflection,light undergoes a 180° phase change:
A)always.
B)if the incident medium has the higher index of refraction.
C)if the incident medium has the lower index of refraction.
D)whenever the incident angle is less than the critical angle.

Question

Quizplus · Accepted Answer

When light travels from a medium with a higher index of refraction to a medium with a lower index of refraction, it undergoes a 180° phase change upon reflection. This is known as a "pi-phase shift" and is due to the change in the speed of light as it crosses the boundary between the two media. Therefore, choice C is correct. Choices A, B, and D are incorrect because they do not take into account the relative indices of refraction between the two media.

Upon Reflection,light Undergoes a 180° Phase Change