The given lens is broken into four parts and rearranged as shown....

The given lens is broken into four parts and rearranged as shown. If the initial focal length is

f

then after rearrangement the equivalent focal length is- The given lens is broken into four parts and rearranged as shown. If the initial focal length is f then after

The given lens is broken into four parts and rearranged as shown. If the initial focal length is f then after

Options

A $f$
B $f / 2$
C $f / 4$
D $4 f$

Correct answer

B. $f / 2$

Step-by-step solution

Cutting a lens in transverse direction doubles their focal length i.e.

2 f

. Using the formula of equivalent focal length,

\frac{1}{f}=\frac{1}{f_{1}}+\frac{1}{f_{2}}+\frac{1}{f_{3}}+\frac{1}{f_{4}}

We get equivalent focal length as

f / 2

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