# Glass wedge

1. Apr 18, 2010

### caliver

1. The problem statement, all variables and given/known data
It's not a specific question. It's more of a general knowledge. As you know, an air wedge forms when two glass plates have one ends meeting each other and the other ends opening up.
Here's the diagram: http://1.bp.blogspot.com/_g3mLW-twYGc/R-EDX7CqirI/AAAAAAAAALc/v7csfR3s8Vc/s400/wedge1.bmp

And in this air wedge, a dark spot forms at the edge due to destructive interference.

But, what happens if the wedge is reversed? So instead of having two glass plates, what if there is a glass wedge with "air plates"?
Would the pattern be inverted?

2. Relevant equations
constructive 2t = (m+1/2) lambda
destructive 2t = (m) lambda

3. The attempt at a solution
I think the pattern will be the same because there is another destructive interference (a phase difference of pi) at the edge. Correct me if I am wrong.

2. Apr 19, 2010

### ehild

" Relevant equations
constructive 2t = (m+1/2) lambda
destructive 2t = (m) lambda"

If the wedge is made from a medium of refractive index N, the equations will hold for N*t instead of t.

ehild