# Homework Help: Phase difference after passing through liquid and glass

1. Feb 19, 2016

### magnesium12

1. The problem statement, all variables and given/known data
Two waves travel next to each other for 100cm.
Wave A passes through a glass container containing liquid. The thickness of the glass in total is 1cm and the width of the liquid is 10cm. The glass has n = 1.52 and the liquid has n=1.33.
Wave B passes through a vacuum and has wavelength 500nm.
Both waves start out in phase. Find the relative phase differences at the finishing line (after 100cm).

2. Relevant equations
c/n = λv (?)

3. The attempt at a solution
I'm not sure where to start.
I was thinking that the phase difference will be proportional to the difference in time it takes to get to the finish line.
Δφ = Δt
But I have no idea how to find the difference in the time it takes for each wave to get to the end.

2. Feb 19, 2016

### BvU

You need to rethink (or look up) your equations. Dimensions don't match in both cases !

3. Feb 19, 2016

### magnesium12

So I found this: Δφ/2π = Δt/vo
And then t = c/λ and I find the new wavelength for each section of path B with c/nv and then add up the times?