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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumMulti-step

JEE Main 25 July 2021, Shift 2, Physics Q26

Question 26 of 90 in this shift, Physics question 26 of 30, Section B.

A 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 electrons emitted perpendicular to the magnetic field B, with maximum kinetic energy are bent into circular arc of radius 30 cm. The value of B is __________ ×10−7\times10^{-7} T. Given hc=20×10−2620\times10^{-26} J-m, mass of electron=9×10−319\times10^{-31} kg

Official answer

125

NTA final key.

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. 9 Jan 2020, Shift 1 · Q18Radiation, with wavelength 6561 A˚\mathrm{\AA} falls on a metal surface to produce photoelectrons. The electrons are made to enter a…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.