Question

write an expression for the lateral displacement of the fringes when a thin transparent sheet is inserted in the path of one the interfering Beams. (follow me)​

Answer 1

Answer:

When a film of thickness’t’ and refractive index 'm' is introduced in the path of one of the sources, then fringe shift occurs as the optical path difference changes.

Optical path difference changes

Optical path difference at

P = S2P - [S1P+ µt - t] = S2P - S1P - (µ - 1)t = y.d/D - (µ - 1)

⇒ nth fringe is shifted by Δy = D(µ-1)t/d = w/λ (µ-1)t

Illustration:

Monochromatic light of wavelength of 600 nm is used in a YDSE. One of the slits is covered by a transparent sheet of thickness 1.8 x 10-5 m made of a material of refractive index 1.6. How many fringes will shift due to the introduction of the sheet?

Solution:

As derived earlier, the total fringe shift = w/λ (µ-1)t .

As each fringe width = w,

The number of fringes that will shift = total fringe shift/fring width

(w/λ(µ-1)t)/w = (µ-1)t/λ = (1.6-1) x 1.8 x 10-5m / 600 x 10-9 = 18

HOPE IT HELPS YOU

Answer 2

INBOX KARO YLL ...............PLS !