A soap bubble film that is 106 nm thick and has an index of refraction of 1.42 results in constructive interference in the reflected light if this film is illuminated by a beam of light with a
Wavelength of 601 nm. What are the next three thicknesses of this film that will also result in
Constructive interference?

Question

Quizplus · Accepted Answer

The correct answer is A because the next three thicknesses of the film that will also result in constructive interference are 318 nm, 530 nm, and 742 nm. This is because the condition for constructive interference is that the path length difference between the two waves reflected from the two surfaces of the film must be an integer multiple of the wavelength of the light. In this case, the path length difference is 2nt, where n is the index of refraction of the film and t is the thickness of the film. Therefore, the condition for constructive interference is 2nt = mλ, where m is an integer. For the given wavelength of 601 nm and index of refraction of 1.42, the next three thicknesses of the film that will result in constructive interference are 318 nm, 530 nm, and 742 nm.

A Soap Bubble Film That Is 106 Nm Thick and Has