Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
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-

PhysicsRay OpticsBITSATBITSAT 2013
Options:
  • A $f$
  • B $f / 2$
  • C $f / 4$
  • D $4 f$
Solution:
1122 Upvotes Verified Answer
The correct answer is: $f / 2$
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 $f / 2$

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.