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Physics · Geometrical Optics

JEE Main 2026 — 4 April, Evening Shift — Question 15

A convex lens is made from glass material having refractive index of 1.4 with same radius of curvature on both sides. The ratio of its focal length and radius of curvature is

  1. Option A:

    0.5

  2. Option B:

    2.5

  3. Option C:

    0.8

  4. Option D:

    1.25

    Correct

Answer: D

Step-by-step solution

Lens maker formula: 1f=(n−1)(1R−1−R)=(0.4)(2R)=0.8R\frac{1}{f} = (n-1)\left(\frac{1}{R} - \frac{1}{-R}\right) = (0.4)\left(\frac{2}{R}\right) = \frac{0.8}{R}. Hence f/R=1/0.8=1.25f/R = 1/0.8 = 1.25.

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Paper
4 April, Evening Shift
Subject
Physics
Chapter
Geometrical Optics
Topic
Lenses and Their Combinations, Silvering of Lens
A convex lens is made from glass material having refractive index of… | JEE Main 2026 PYQ with Solution · DhiX AI