# Double slit arrangment?

1. Apr 3, 2004

### Callisto

Double slit arrangment??

Can any body help me with this problem?

A thin flake of mica(n=1.58) is used to cover one slit of a double slit interference arrangment.The central point on the viewing screen is now covered by what had been the 5th bright fringe before the mica was used. Find the thickness of the mica if light of wavelength 572nm is used?

Any hints or tips are very much appreciated.

Callisto

2. Apr 3, 2004

### Dr Transport

The problem is that of finding the path difference or phase difference between the two systems. Calculate the diffraction problem without the mica involved. From there you will know the phase and can go on to solve the other part.

dt

3. Apr 3, 2004

### himanshu121

the path differnce will be

$$[n-1]t - \frac{dy}{D}$$

Now ,given condition $$y= \frac{5 \lambda D}{d}$$

and $$[n-1]t - \frac{dy}{D} =0$$ for central maxima/point

4. Apr 3, 2004