Question

A glass window is coated with a transparent film of refractive index n2 =1.25. This film will cause destructive interference in the reflected light when light of wavelength λ = 550nm is incident normally on the window. What is the minimum thickness of film required to produce this anti-reflection coating?

Answer 1

0.00000011 m

Step-by-step explanation:

n = 0 for minimum thickness

t = Thickness

`n_2` = Refractive index of the film = 1.25

`\lambda` = Wavelength =
`550* 10^(-9)\ m`

We have the formula

`2n_2t=(2n+1)(\lambda)/(2)`

`\\\Rightarrow t=(2n+1)(\lambda)/(4n_2)\\\Rightarrow t=(2* 0+1)(550* 10^(-9))/(4* 1.25)\\\Rightarrow t=0.00000011\ m`

The minimum thickness of the film is 0.00000011 m