﻿ When a thin wedge-shaped film is illuminated by a parallel beam of light of wavelength 6000 Ã…, 7 fringes are observed in a certain region of the film. How many fringes will be observed in the same region of the film if light of wavelength 4200 Ã… is used? : Kaysons Education

# When A Thin Wedge-shaped Film Is Illuminated By A Parallel Beam Of Light Of Wavelength 6000 Ã…, 7 Fringes Are Observed In A Certain Region Of The Film. How Many Fringes Will Be Observed In The Same Region Of The Film If Light Of Wavelength 4200 Ã… is Used?

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## Question

### Solution

Correct option is

10

n fringes of wavelength λ are confined in a region x given by

Where l = length of the film and s its maximum thickness. Thus nλ = constant, i.e.

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