What is the thinnest soap film (excluding the case of zero thickness) that appears black when illuminated with light with a wavelength of 555 nmnm

The minimum thickness of soap film is .

Explanation:

wavelength = 555 nm

refractive index, n = 1.33

For the destructive interference,

the thickness is given by

Here, m is the order, n is the refractive index and is the wavelength.

For minimum thickness, m = 1

So the thickness is  

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