# Electromagnetic wave before and after refraction

## Homework Statement

This question is question 5 from chapter 4 of Hecht's Optics, 4th edition. I found a pdf of the homework set, and the question is labeled as 4.5. http://www.physics.byu.edu/faculty/hess/471W09/Homework/Ch4.pdf" [Broken]

## Homework Equations

Not completely sure

## The Attempt at a Solution

I saw my professor for help with this problem, and he told me that we have to find the phase difference in between the incident ray and the transmitted ray (from glass to air). If there are any other important pieces of advice or hints or possible diving boards from which I can jump into this problem, I would greatly appreciate any help you can provide. Thanks!!!

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For starters, when you look at the expression given for $E_u$, can you tell which direction the wave is propagating? Which direction would such an incident wave travel once inside the glass plate? How about after it leaves it again?