JEE Main 2021PhysicsDual Nature of MatterMediumNumerical

JEE Main 2021Dual Nature of Matter Question with Solution

JEE Main 2021 (20 Jul Shift 2)

Question

A certain metallic surface is illuminated by monochromatic radiation of wavelength . The stopping potential for photoelectric current for this radiation is 3 V0. If the same surface is illuminated with a radiation of wavelength 2λ, the stopping potential is V0. The threshold wavelength of this surface for photoelectric effect is___________λ.

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Show full solutionCorrect answer: 4
Correct answer
4

Step-by-step explanation

KE=hcλ-ϕhc

e3V0=hcλ0-ϕ  i

eV0=hc2λ0-ϕ  ii

Using i and ii,

ϕ=hc4λ0=hcλt

λt=4λ0

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About this question

This is a previous-year question from JEE Main 2021, covering the Dual Nature of Matter 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.