Optics Question 823

Question: Two identical thin Plano convex lenses of refractive index n are silvered, one on the plane side and the other on the convex side. The ratio of their focal lengths is

Options:

A) nn1

B) n1n

C) n+1n

D) n

Show Answer

Answer:

Correct Answer: A

Solution:

[a] 1f=2fe+2fm

fm=R2 fm=0

1fe=n1R fe=n1R f2=R2n

f1=R2(n1) Ratiof1f2=nn1



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