Question

A thin film of thickness t and index of refraction
1.33 coats a glass with index of refraction 1.5.
What is least thickness t that will strongly reflect
light with wavelength 600nm incident normally
(1) 225 nm
(2) 300 nm
(3), 400 nm
(4) 450 nm​

Answer 1

Answer:

Explanation:

=>Expression of Least thickness t that will strongly reflect  light:

since, t = nλ/2μ

Here,

λ = Wavelength = 600 nm

μ = Refractive index of film = 1.33

For least thickness : n = 1

Hence,

t = λ / 2μ

= 600 / 2*1.33

= 600/ 2.66

= 225.56

≈ 225 nm

Thus, least thickness t that will strongly reflect  light with wavelength 600nm incident normally is 225 nm.