Question

on introducing a thin film in the path of one of the two interfering beam,the central fringe will shift by one fringe width. if refractive index =1.5, the thickness of the film is (wavelength of monochromatic light is lambda
a)4 lambda
b)3 lambda
c)2 lambda
d)1 lambda​

Answer 1

Answer:

2λ

Explanation:

Shift = Δ€

Width of one fringe = λ

Δ€=(μ−1)t=1λ

For one maximum shift :

t× (μ−1)=λ

=} t×(1.5-1)=λ

=} t= 2 λ

t = thickness of the thin film

λ = wavelength of monochromatic light