- #1

vetgirl1990

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## Homework Statement

Two parallel glass plates of index of refraction n

are separated by an air film of thickness d. Light of wavelength λ

in air, normally incident on the plates, is intensified

on reflection when, for some integer m

a) 2d=mλ

b) 2d=mλ/n

c) 2d=mnλ

d) 2d=(m+1/2)λ

e) 2d=mλ/2

## Homework Equations

If only one ray is π shifted: 2nd=mλ (min), 2nd=(m+1/2)λ (max)

If both rays π shifted: 2nd=mλ (max), 2nd=(m+1/2)λ (min)

## The Attempt at a Solution

I've attached a diagram of two different for how I picture light should be transmitted in this problem. I'm not sure which one would be a correct approach.

Going with the first diagram,

This would result in a net π shift, so it's conditions would be 2nd=mλ (min) and 2nd=(m+1/2)λ (max).

I chose answer

**(B) 2d=mλ/n**, since the question asks for "intensity increase" so I am assuming it is asking about the condition for a bright fringe; and also because it's one of the only options that takes the index of refraction (n) into account.

I would just like to verify that my reasoning is correct.

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