# Question regarding a double slit experiment

1. May 3, 2013

### Dongorgon

1. The problem statement, all variables and given/known data

The question is as follows, I'm truly stuck where to start here, any help would be much appreciated:

A transparent paper of refractive index 1.45 and thickness 0.02mm is pasted on one of the slits of a double slit experiment. Monochromatic light of wavelength 620nm is passed through the slits. How many fringes will cross through the centre if the paper is removed?

2. Relevant equations

I have been provided with one equation for this, which is as follows:

Yo=β/λ(n-1)t

Where n is the refractive index and t is the thickness.

3. The attempt at a solution

Truly stuck where to even begin I'm sorry to say.

2. May 3, 2013

### SammyS

Staff Emeritus
What are β and Yo in this equation? (I take it that λ is wavelength.)

3. May 3, 2013

### Dongorgon

From what I am aware, β is the fringe width and I'm truly not sure what Yo even is, possibly the width of intensity?