Question

a wedge shaped air film is illustrated by a light of wavelength 4650 angstrom.The angle of wedge is 40°.The fringe width between any two consecutive fringe is​

Answer 1

$\huge\star{\underline{\mathtt{\red{A}\pink{N}\green{S}\blue{W}\purple{E}\orange{R}}}}⋆$

In thin wedge - shaped film

2μd=nλ

where, μ is refractive index of the film

d is separation between two surfaces

n is number of fringes

λ is wavelength of light

So, here in the problem we are changing the wavelength of the light keeping μ and d same

So, n will change such that nλ will remain same.

so, n 1 λ 1 =n 2 λ 2

7×6000=n 2 × 4200

=> =10

Answer 2

The fringe width between any two consecutive fringes is 3.332 × 10^-5 cm.

Given: The wavelength of light is 4650 Å and the angle of the wedge is 40°.

To Find: The fringe width between any two consecutive fringes.

Solution:

We know that the formula to find the fringe width between any two consecutive fringes ( assuming bright fringes ) can be given by;

              β = λ / 2Ф                                                            ....(1)

Where β = Fringe width, λ = wavelength, Ф = angle in radians.

Coming to the numerical, we are given;

The wavelength of light = 4650 Å = 4650 × 10^-8 cm

The angle of wedge is =  40° = 40° × ( π / 180 ) radians

Putting respective values in (1), we get;

              β = λ / 2Ф        

         ⇒  β =  ( 4650 × 10^-8 ) / ( 2 × 40° × ( π / 180 ))

         ⇒  β =  ( 4650 × 10^-8 ) /  1.395

         ⇒  β =  3.332 × 10^-5 cm

Hence, the fringe width between any two consecutive fringes is 3.332 × 10^-5 cm.

#SPJ2