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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 9 January 2020, Shift 1, Physics Q18

Question 18 of 75 in this shift, Physics question 18 of 25, Section A.

Radiation, with wavelength 6561 A˚\mathrm{\AA} falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of 3×10−43\times10^{-4} T. If the radius of the largest circular path followed by the electrons is 10 mm, the work function of the metal is close to :
  1. (1)0.80.8 eV
  2. (2)1.11.1 eVOfficial answer
  3. (3)1.61.6 eV
  4. (4)1.81.8 eV

Official answer

Option 2

NTA final key (Jan 2020).

Chapter
Dual Nature of Radiation and Matter
Topic
Photoelectric Effect
Idea tested
Photoelectrons in a Magnetic Field

Same idea in other shifts

Asked 2× in all
  1. 25 Jul 2021, Shift 2 · Q26A light beam of wavelength 500 nm is incident on a metal having work function of 1.25 eV, placed in a magnetic field of intensity B. The…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 108 of the 174 JEE Main shifts held from 2017 to 2026.