Question

Is there a phase change in the light reflected from either surface of a contact lens floating on a person’s tear layer? The index of refraction of the lens is about 1.5, and its top surface is dry.

a. Yes, there is a phase change at both surfaces.
b. No, there is no phase change at either surface.
c. Yes, there is a phase change only at the top surface.
d. Yes, there is a phase change only at the bottom surface.

Answer 1

Yes, there is a phase change at both surfaces.

Step-by-step explanation:

The light reflected from the top and bottom surfaces of a contact lens floating on a person's tear layer undergoes a phase change. When light reflects from a medium with a higher index of refraction, such as the contact lens, compared to the medium it is traveling in, a 180° phase change (or a λ/2 shift) occurs.

Therefore, the correct answer is option a. Yes, there is a phase change at both surfaces.