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.

thinnest soap film is  206.76 nm

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 × m

and n = 1.3

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

thickness = λ/2n

thickness = 550 ×  / 2(1.33)

thickness = 206.76 ×  m

thinnest soap film is  206.76 nm

the answer is a. at the equator