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Friday, 9 October

JEE Main 2025 · PhysicsMultiple choiceSingle correctMediumConceptual

JEE Main 2 April 2025, Shift 2, Physics Q33

Question 33 of 75 in this shift, Physics question 8 of 25, Section A.

An electron with mass mm with an initial velocity (t=0)(t=0) v⃗=v0i^\vec{v} = v_0\hat{i} (v0>0)(v_0 > 0) enters a magnetic field B⃗=B0j^\vec{B} = B_0\hat{j}. If the initial de-Broglie wavelength at t=0t = 0 is λ0\lambda_0 then its value after time tt would be :
  1. (1)λ0\lambda_0Official answer
  2. (2)λ01+e2B02t2m2\lambda_0\sqrt{1+\frac{e^2B_0^2t^2}{m^2}}
  3. (3)λ01−e2B02t2m2\frac{\lambda_0}{\sqrt{1-\frac{e^2B_0^2t^2}{m^2}}}
  4. (4)λ01+e2B02t2m2\frac{\lambda_0}{\sqrt{1+\frac{e^2B_0^2t^2}{m^2}}}

Official answer

Option 1

NTA final key.

Chapter
Dual Nature of Radiation and Matter
Topic
Matter Waves
Idea tested
Wavelength in a Uniform Magnetic Field

Same topic in other shifts

All Matter Waves questions
  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. 5 Apr 2026, Shift 1 · Q35An electron of mass mm is moving in an electric field E⃗=−2E0i^\vec{E} = -2E_0\hat{i} (E0E_0 = constant >0> 0), with an initial velocity…MediumSingle correct
  3. 5 Apr 2026, Shift 2 · Q43An electron is travelling with a velocity vv in free space and when it enters a medium, its velocity is reduced by 20%. The de Broglie…EasySingle correct
  4. 6 Apr 2026, Shift 2 · Q47The de Broglie wavelength for an electron accelerated through the potential difference of V1V_1 volt is λ1\lambda_1. When the potential…EasyNumerical value
  5. 7 Apr 2025, Shift 2 · Q43A photoemissive substance is illuminated with a radiation of wavelength λi\lambda_i so that it releases electrons with de-Broglie…MediumSingle correct
  6. 8 Apr 2025, Shift 2 · Q50An electron is released from rest near an infinite non-conducting sheet of uniform charge density '−σ-\sigma' .The rate of change of…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.