In: Physics
A very thin oil film (n=1.25) floats on water (n=1.33).
What is the thinnest film that produces a strong reflection for green light with a wavelength of 500 nm?
d=________nm
Data:
Wavelength of light, λ = 500 nm
= 500 x 10^-9 m
Refractive index of oil, n1 = 1.25
Refractive index of water, n2 = 1.33
Thickness of the film, d = ?
Solution:
For strong reflection, m = 1
Wavelength, λ= 2 n1 d / m
Thickness, d = λ m / 2 n1
= 500 x 10 -9 * 1 / ( 2 * 1.25 )
= 200 x 10 -9 m
= 200 nm