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Friday, 9 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 18 March 2021, Shift 1, Physics Q8

Question 8 of 90 in this shift, Physics question 8 of 30, Section A.

A particle is travelling 4 times as fast as an electron. Assuming the ratio of de-Broglie wavelength of a particle to that of electron is 2 : 1, the mass of the particle is :
  1. (1)8 times the mass of e−^-
  2. (2)116\frac{1}{16} times the mass of e−^-
  3. (3)16 times the mass of e−^-
  4. (4)18\frac{1}{8} times the mass of e−^-Official answer

Official answer

Option 4

NTA final key.

Chapter
Dual Nature of Radiation and Matter
Topic
Matter Waves
Idea tested
Wavelength Ratios of Different Particles

Same idea in other shifts

Asked 3× in all
  1. 4 Apr 2026, Shift 2 · Q44The de Broglie wavelength associated with an electron accelerated through a potential difference V is λe\lambda_e and the de Broglie…EasySingle correct
  2. 16 Mar 2021, Shift 2 · Q2The de-Broglie wavelength associated with an electron and a proton were calculated by accelerating them through same potential of 100 V.…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 42 of the 174 JEE Main shifts held from 2017 to 2026.