Monochromatic light (λ = 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

The thickness of the bubble is equal to λ/4n, where λ is the wavelength of light and n is the refractive index of the bubble. In this case, λ = 500 nm and n = 1.40, so the thickness of the bubble is 500 nm / (4 * 1.40) = 89.3 nm.

Monochromatic Light (λ = 500 Nm) Is Incident on a Soap