Question

What is the thinnest soap film (excluding the case of zero thickness) that appears black when illuminated with light with a wavelength of 550 nm ? The index of refraction of the film is 1.33, and there is air on both sides of the film.

Answer 1

thinnest soap film is 206.76 nm

Step-by-step explanation:

Given data

wavelength = 550 nm

index of refraction n = 1.33

to find out

What is the thinnest soap film

solution

we have wavelength λ = 550 nm

that is λ = 550 ×
`10^(-9)` m

and n = 1.3

we will find the thickness of soap film as given by formula that is

thickness = λ/2n

thickness = 550 ×
`10^(-9)` / 2(1.33)

thickness = 206.76 ×
`10^(-9)` m

thinnest soap film is 206.76 nm