JEE Main 2025 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 7 April 2025, Shift 2, Physics Q40

Question 40 of 75 in this shift, Physics question 15 of 25, Section A.

A mirror is used to produce an image with magnification of

\frac{1}{4}

. If the distance between object and its image is 40 cm, then the focal length of the mirror is __________.

(1)10 cm
(2)10.7 cmOfficial answer
(3)15 cm
(4)12.7 cm

Official answer

Option 2

NTA final key.

Chapter: Ray Optics and Optical Instruments
Topic: Spherical Mirrors
Idea tested: Mirror Formula Application

Same idea in other shifts

Asked 3× in all

6 Apr 2026, Shift 2 · Q50A concave mirror of focal length 10 cm forms an image which is double the size of object when the object is placed at two different…MediumNumerical value
27 Aug 2021, Shift 1 · Q16An object is placed beyond the centre of curvature C of the given concave mirror. If the distance of the object is $\mathrm{d}_1$ from C…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.