Solving for Mica Thickness in Double Slit Interference Arrangement

[Callisto]

Double slit arrangment??

Can anybody 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?

Where do i start with such a problem?
Any hints or tips are very much appreciated.

Callisto

 

[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

 

[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

 

[Callisto]

Thankyou for your replies,
they where of great assistance