Physics · Geometrical Optics

JEE Main 2026 — 21 January, Morning Shift — Question 43

A collimated beam of light of diameter 2 mm is propagating along x -axis. The beam is required to be expanded in a collimated beam of diameter 14 mm using a system of two convex lenses. If first lens has focal length 40 mm , then the focal length of second lens is $\_\_\_\_$ mm .

Answer: 280

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Step-by-step solution

\frac{40}{2}=\frac{f}{14}

$\Rightarrow \mathrm{f}=280 \mathrm{~mm}$

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Exam: JEE Main 2026
Paper: 21 January, Morning Shift
Subject: Physics
Chapter: Geometrical Optics
Topic: Lenses and Their Combinations, Silvering of Lens

In a microscope the objective is having focal length f 0=2 cm and eye-piece is having focal length f e=4 cm . The tube length is 32 cm .…

Answer: 280

Step-by-step solution

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