Question

A wedge shaped film of refractive index μ has thickness t1 and t2 at two points. When a light of wavelength λ falls on the film. The number of changes observed between these two points is m. Find the difference
t2 - t1.​

Answer 1

Explanation:

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

⇒n

2

=10