Question

Suppose that in a double slit experiment, you were to cover the upper-most slit with a sliver of crown glass (refractive index n ≈ 1.52) whose thickness t ensures that none of the light incident on the sliver is reflected back through the slit. You may assume a red laser beam of wavelength 650 nm.

In this given scenario: What are the phase changes in the reflected waves on the left and right side of the glass silver?

Answer 1

So reflection at the interface of rarer (air) to denser (crown glass) results in phase chaange of pi in reflected ray while ray reflected from the denser (crown glass) to rarer (air ) changes no extra phase . So due this we write total path difference between this two rays is

here n is refractive index

Now for destructive interferance

we get

and thickness of silver plate then

for m=1 minimum thickness