JEE Main 2020PhysicsDual Nature of MatterMediumMCQ

JEE Main 2020 — Dual Nature of Matter Question with Solution

JEE Main 2020 (08 Jan Shift 1)

Question

When photon of energy 4.0eV strikes the surface of a metal A, the ejected photoelectrons have maximum kinetic energy TAeV and de-Broglie wavelength λA. The maximum kinetic energy of photoelectrons liberated from another metal B by photon of energy 4.50eV is TB=TA-1.5eV. If the de-Broglie wavelength of these photoelectrons λB=2λA, then the work function of metal B is:

Choose an option

Show full solutionCorrect option: A
Correct answer
A4eV

Step-by-step explanation

Relation between de-Broglie wavelength and K.E. is
λ=h2(KE)me⇒λ∝1KE
λAλB=KEBKEA
⇒12=TA-1.5TA⇒TA=2 eV
∴KEB=2-1.5=0.5 eV
ϕB=4.5-0.5=4 eV

Practice this on the real CBT interface

Solve this JEE Main question (and the rest of the Dual Nature of Matter chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.

Solve interactively →

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.