White light is shone on a very thin layer of mica (n = 1.57).When the mica layer is observed from the illuminated side,interference maxima for wavelengths of blue (480 nm) and yellow (560 nm)are observed.What is the thickness of the mica layer?
A) 1.58 $\mu$m
B) 0.79 $\mu$m
C) 3.16 $\mu$m
D) insufficient information is given.

Question

Quizplus · Accepted Answer

The thickness of the mica layer is equal to one-half of the wavelength of the light in the medium. For blue light, the wavelength in the medium is 480 nm / 1.57 = 306 nm. For yellow light, the wavelength in the medium is 560 nm / 1.57 = 357 nm. The thickness of the mica layer is therefore (306 nm + 357 nm) / 2 = 1.58 µm.

White Light Is Shone on a Very Thin Layer of Mica