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## Homework Statement

Monochromatic light of wavelength, λ is traveling in air. The light then strikes a thin film having an index of refraction n1 that is coating a material having an index of refraction n2. If n2 is larger than n1, what minimum film thickness will result in minimum reflection of this light?

Multiple choice:

A λ/n1

B λ/(4n1)

C λ/n2

D λ/2

E λ

F λ/(4n2)

G λ/(2n1)

H λ/4

I λ/(2n2)

J The correct response is not shown above.

## Homework Equations

2t = m*λ/n

2t = (m+0.5)*λ/n

where m is an integer, n is the refraction index of light, and t is thickness.

## The Attempt at a Solution

So I believe the wave is destructive because there are 2 phase changes. One when light enters it and the second when it hits passes the coating. Therefore the equation is the second one. I reasoned M must be zero because otherwise I would get a number in the numerator when there is not one in the multiple choice. So if we dived the 2 we get t = λ/4n(something) I don't know if the n is supposed to be 1 or 2.

Any help is greatly appreciated!