Monochromatic light ($\lambda$ = 500 nm)is incident on a soap bubble (n = 1.40).How thick is the bubble (in nm)if destructive interference occurs in the reflected light?
A)102
B)179
C)54
D)1
E)89

Question

Quizplus · Accepted Answer

Destructive interference occurs when the path length difference between the two reflected waves is half a wavelength. The path length difference is 2nt, where n is the index of refraction of the bubble and t is the thickness of the bubble. So, 2nt = 500 nm/2 = 250 nm. Therefore, t = 250 nm/1.40 = 178.57 nm.

Monochromatic Light λ\lambdaλ = 500 Nm)is Incident on a Soap Bubble (N =

Monochromatic Light $\lambda$ = 500 Nm)is Incident on a Soap Bubble (N =