Ray Optics

JEE Main level, numerical answer, medium

42 of 295

Question 42 of 295

When an object is kept at a distance of 30cm30cm from a concave mirror, the image is formed at a distance of 10cm10cmfrom the mirror. If the object is moved with a speed of 9cms−19cm{s}^{-1} , the speed (in cms−1cm{s}^{-1}) with which image moves at that instant is

Show answer and solution

Answer: 1

Velocity of image
vi=−v2u2×v0{v}_{i}=-\dfrac{{v}^{2}}{{u}^{2}}\times {v}_{0}
=−102302(9)=-\dfrac{{10}^{2}}{{30}^{2}}\left(9\right)
=−1cmsec⁡−1=-1cm{\sec }^{-1}

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.
See it move: Lens ray diagram simulationDrag the sliders and watch the numbers in this question change.Revise Ray Optics firstFormula sheet, solved examples and the traps students fall into.

More Physics practice

JEE Main Physics practice question on Ray Optics (Mirror Formula, Reflection in Spherical Mirror), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.