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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceAssertion–reasonEasyConceptual

JEE Main 26 February 2021, Shift 1, Physics Q18

Question 18 of 90 in this shift, Physics question 18 of 30, Section A.

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : An electron microscope can achieve better resolving power than an optical microscope. Reason R : The de Broglie’s wavelength of the electrons emitted from an electron gun is much less than wavelength of visible light. In the light of the above statements, choose the correct answer from the options given below :
  1. (1)Both A and R are true and R is the correct explanation of A.Official answer
  2. (2)Both A and R are true but R is NOT the correct explanation of A.
  3. (3)A is true but R is false.
  4. (4)A is false but R is true.

Official answer

Option 1

NTA final key.

Chapter
Dual Nature of Radiation and Matter
Topic
Matter Waves
Idea tested
Electron Specific Wavelength Formula

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. 2 Apr 2025, Shift 2 · Q33An 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…MediumSingle correct
  6. 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

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.