Dual Nature of Matter

JEE Main level, single correct, medium

154 of 200

Question 154 of 200

An electron and proton are separated by a large distance. The electron starts approaching the proton with energy 3eV3eV. The proton captures the electrons and forms a hydrogen atom in second excited state. The resulting photon is incident on a photosensitive metal of threshold wavelength 4000A4000A What is the maximum kinetic energy of the emitted photoelectron?

Show answer and solution

Answer: (B) 1.41eV1.41eV

Initially, energy of electron =+3eV=+3eV
finally, in 2nd{2}^{nd} excited state,
energy of electron =−(13.6eV)32=-\dfrac{(13.6eV)}{{3}^{2}}
=−1.51eV=-1.51eV
Loss in energy is emitted as photon,
So, photon energy hcλ=4.51eV\dfrac{hc}{\lambda }=4.51eV
Now, photoelectric effect equation
KEmax⁡=hcλ−ϕ=4.51−(hcλth){KE}_{\max }=\dfrac{hc}{\lambda }-\phi =4.51-\left(\dfrac{hc}{{\lambda }_{th}}\right)
=4.51eV−12400eVA4000A=4.51eV-\dfrac{12400eVA}{4000A}
=1.41eV=1.41eV

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: Photoelectric effect and matter waves simulationDrag the sliders and watch the numbers in this question change.Revise Modern Physics firstFormula sheet, solved examples and the traps students fall into.

More Physics practice

JEE Main Physics practice question on Dual Nature of Matter (Photoelectric Effect), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.