Question

An oil film with index of refraction 1.64 is trapped between two pieces of glass with index of refraction 1.43. No light is reflected by such a film when 578 nm light falls on it at normal incidence. What is the nonzero minimum thickness of the oil film that will satisfy these conditions? Answer in units of nm.

Answer 1

176.22 nm

Step-by-step explanation:

`n` = Index of refraction of oil = 1.64

`\lambda` = Wavelength of the light = 578 nm

`t` = minimum thickness of the oil

For destructive interference, we have

`2nt = m \lambda`

For minimum thickness, m = 1

`2(1.64)t = (1) (578)\\3.28 t = 578\\t = 176.22 nm`