A silicon monoxide thin film (n = 1.45)of thickness 90.0 nm is applied to a camera lens made of glass (n = 1.55).This will result in a destructive interference for reflected light of what wavelength?

Question

Quizplus · Accepted Answer

We can use the formula for the thickness of a thin film causing destructive interference for reflected light:

t = (m + 1/2)λ / (2n)

where t is the thickness of the film, λ is the wavelength of light, n is the refractive index of the film, and m is the number of the interference order.

For destructive interference, m is an odd integer. We can rearrange the formula to solve for λ:

λ = 2nt / (m + 1/2)n

For the given values,

t = 90.0 nm
n1 = 1.45 (refractive index of the silicon monoxide film)
n2 = 1.55 (refractive index of the glass lens)

We want destructive interference, so we can use m = 1. Plugging in the values,

λ = 2(1.45)(90.0 nm) / (1 + 1/2)(1.55) = 522 nm

Therefore, the wavelength of light that will experience destructive interference is 522 nm, so the answer is C.

A Silicon Monoxide Thin Film (N = 1