A surface is coated with a material having index of refraction 1.50.If light in air has a wavelength of 450 nm and is normally incident on this surface,and it is found through interference effects with this light that the surface is 10 wavelengths thick,which of the following is the thickness of the surface?
A)1.5 ìm
B)3.0 ìm
C)4.5 ìm
D)6.8 ìm

Question

Quizplus · Accepted Answer

The thickness of the surface is calculated by multiplying the wavelength of light in the material by the number of wavelengths. The wavelength in the material is the wavelength in air divided by the index of refraction: 450 nm / 1.50 = 300 nm. The thickness is then 300 nm * 10 = 3000 nm = 3.0 µm.

A Surface Is Coated with a Material Having Index of Refraction