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Friday, 9 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 8 January 2020, Shift 1, Physics Q17

Question 17 of 75 in this shift, Physics question 17 of 25, Section A.

When photon of energy 4.0 eV strikes the surface of a metal A, the ejected photoelectrons have maximum kinetic energy TAT_A eV and de-Broglie wavelength λA\lambda_A. The maximum kinetic energy of photoelectrons liberated from another metal B by photon of energy 4.50 eV is TB=(TA−1.5)T_B = (T_A - 1.5) eV. If the de-Broglie wavelength of these photoelectrons λB=2λA\lambda_B = 2\lambda_A, then the work function of metal B is :
  1. (1)1.5 eV
  2. (2)4 eVOfficial answer
  3. (3)3 eV
  4. (4)2 eV

Official answer

Option 2

NTA final key (Jan 2020).

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

Same idea in other shifts

Asked 4× in all
  1. 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
  2. 9 Apr 2024, Shift 2 · Q47UV light of 4.134.13 eV is incident on a photosensitive metal surface having work function 3.133.13 eV. The maximum kinetic energy of ejected…EasySingle correct
  3. 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 v1v_1.…MediumNumerical value

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 42 of the 174 JEE Main shifts held from 2017 to 2026.