Working with Wedge Fringes

1. Mar 13, 2006

Vixus

For a solid wedge of material of length L and maximum width D (ie, a triangle) how would one obtain an equation for /\x, the distance between dark fringes?

For wedge fringes, how come the fringe at the narrow end is always dark?

2. Mar 13, 2006

Staff: Mentor

You need to consider two factors that determine the phase difference--and thus the interference--between the reflections at each boundary:

What is the phase change upon reflection?

What distance does the light travel in passing (twice) through the wedge?​
Read up with these factors in mind.