Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Wave Optics

Question:

When light is incident on a soap film of thickness $5 × 10^{–5} cm$, wavelength reflected maximum in the visible region is 5320 Å. Refractive index of the film will be

Options:

1.22

1.33

1.51

1.83

Correct Answer:

1.33

Explanation:

$2μt\, \cos r =(2n+1)\frac{λ}{2}$

or $μ=\frac{(2n+1)}{2t\, \cos r}\frac{λ}{2}=\frac{(2n+1)×5320×10^{-10}}{2×5×10^{-5}×10^{-2}×1}$

$⇒μ=1.33$