JEE Main 2022PhysicsRay OpticsHardNumerical

JEE Main 2022 — Ray Optics Question with Solution

JEE Main 2022 (25 Jul Shift 2)

Question

A convex lens of focal length 20 cm is placed in front of convex mirror with principal axis coinciding each other. The distance between the lens and mirror is 10 cm. A point object is placed on principal axis at a distance of 60 cm from the convex lens. The image formed by combination coincides the object itself. The focal length of the convex mirror is _____ cm.

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Show full solutionCorrect answer: 10
Correct answer
10

Step-by-step explanation

For lens 1v-1u=1f

⇒1v-1-60=120⇒1v+160=120

v=30 cm

For the final image to be formed on the object itself, after refraction from lens the ray should meet the mirror perpendicularly and the image by lens should be on the centre of curvature of mirror.

R=30-10=20 cm.

Now the focal length of mirror fm=R2=10 cm

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About this question

This is a previous-year question from JEE Main 2022, covering the Ray Optics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.