JEE Main 2021 · PhysicsNumerical answerNumerical valueEasyCalculation

JEE Main 3 August 2021, Shift 1, Physics Q25

Question 25 of 90 in this shift, Physics question 25 of 30, Section B.

A photoelectric metal of work function 1 eV is used for photoelectric effect. When a radiation of wavelength 621 nm is incident on the photometal, the maximum kinetic energy of photoelectrons approximately is _________ (in eV). [Given hc=1242 eV-nm]

Official answer

NTA final key.

Chapter: Dual Nature of Radiation and Matter
Topic: Photoelectric Effect
Idea tested: Einstein's Photoelectric Equation

Same idea in other shifts

Asked 14× in all

5 Apr 2026, Shift 1 · Q41Light source having wavelength 331 nm is used to generate photo-electrons whose stopping potential is 0.2 V. The work function of the used…EasySingle correct
4 Apr 2024, Shift 2 · Q47Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Number of photons…MediumAssertion–reason
6 Apr 2024, Shift 1 · Q47In photoelectric experiment energy of 2.48 eV irradiates a photo sensitive material. The stopping potential was measured to be 0.5 V. Work…EasySingle correct
9 Apr 2024, Shift 2 · Q47UV light of $4.13$ eV is incident on a photosensitive metal surface having work function $3.13$ eV. The maximum kinetic energy of ejected…EasySingle correct
28 Jul 2022, Shift 2 · Q17Two streams of photons, possessing energies equal to five and ten times the work function of metal are incident on the metal surface…EasySingle correct
29 Jul 2022, Shift 1 · Q46The kinetic energy of emitted electron is E when the light incident on the metal has wavelength $\lambda$ . To double the kinetic energy,…MediumSingle correct
24 Jun 2022, Shift 1 · Q56When light of frequency twice the threshold frequency is incident on the metal plate, the maximum velocity of emitted electron is $v_1$ .…MediumNumerical value
28 Jun 2022, Shift 2 · Q47Let $K_1$ and $K_2$ be the maximum kinetic energies of photo-electrons emitted when two monochromatic beams of wavelength $\lambda_1$ and…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.