Question

The YDSE apparatus is modified by palcing an isotropic transperent plate of `mu = 1.5` and thinkness `t = 2 mu m` with tempatature coeffcient `2xx10^(-6) .^(@)C^(-1)` . A light of `6000 Å` units is incident. If the palte heated through a temperature `10 ^(@)C` then number of fringes will cross a particular point on the screen ? `(D =2m, d= 2mm)` .
A. `1000`
B. `5000`
C. `(1000)/(3)`
D. `10^(-4)`

Answer 1

Correct Answer - D
`y = ((mu_(2)-mu_(1))D)/(d), mu_(2) = mu_(1) (1+ alpha Delta t)` , wherer `alpha` is temperature coefficient R.I.
Number of fringes crossed `n = y//beta = ((mu_(2) - mu_(1))t)/(lambda)`