Ray Optics

JEE Main level, single correct, medium

193 of 295

Question 193 of 295

A convex lens of focal length 20cm20cm produces images of the same magnification 2 when an object is kept at two distances x1{x}_{1} and x2(x1>x2){x}_{2}\left({x}_{1}\gt {x}_{2}\right) from the lens. The ratio of x1{x}_{1} and x2{x}_{2} is:

Show answer and solution

Answer: (D) 3:13:1

Given, ∣m∣=2⇒m=±2\left|m\right|=2\Rightarrow m=\pm 2
From this lens formula, 1v+1u=1f\dfrac{1}{v}+\dfrac{1}{u}=\dfrac{1}{f}
uv+1=uf\dfrac{u}{v}+1=\dfrac{u}{f}
1m+1=uf\dfrac{1}{m}+1=\dfrac{u}{f}
u=f(1m+1)u=f\left(\dfrac{1}{m}+1\right)
x1=20(1+12){x}_{1}=20\left(1+\dfrac{1}{2}\right)
x2=20(1−12){x}_{2}=20\left(1-\dfrac{1}{2}\right)
x1x2=31\dfrac{{x}_{1}}{{x}_{2}}=\dfrac{3}{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 (Lens Formula, Refraction of light from curved surface), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.