JEE Main 2020PhysicsDual Nature of MatterMediumNumerical

JEE Main 2020 — Dual Nature of Matter Question with Solution

JEE Main 2020 (07 Jan Shift 1)

Question

A beam of electromagnetic radiation of intensity 6.4× 10 −5 W/ cm 2 is comprised of wavelength, λ=310nm . It falls normally on a metal (work function φ=2eV ) of surface area of 1cm2 . If one in 103 photons ejects an election, total number of electrons ejected in 1s is 10x . hc=1240eVnm,1eV=1.6×10-19J, then x is ___________

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Show full solutionCorrect answer: 11
Correct answer
11

Step-by-step explanation

Energy of photon. E=1240310 nm=4eV>2eV (So photoelectric effect will take place)
=4×1.6×10-19=6.4×10-19joule
Number of photons falling per second
=6.4×10-5×16.4×10-19=1014
Number of photoelectron emitted per second
=1014103=1011

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About this question

This is a previous-year question from JEE Main 2020, 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.