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Friday, 9 October

JEE Main 2025 · PhysicsMultiple choiceAssertion–reasonMediumConceptual

JEE Main 3 April 2025, Shift 2, Physics Q40

Question 40 of 75 in this shift, Physics question 15 of 25, Section A.

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A : If Oxygen ion (O−2\mathrm{O^{-2}}) and Hydrogen ion (H+\mathrm{H^+}) enter normal to the magnetic field with equal momentum, then the path of O−2\mathrm{O^{-2}} ion has a smaller curvature than that of H+\mathrm{H^+}. Reason R : A proton with same linear momentum as an electron will form a path of smaller radius of curvature on entering a uniform magnetic field perpendicularly. 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
  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 falseOfficial answer
  4. (4)A is false but R is true

Official answer

Option 3

NTA final key.

Chapter
Moving Charges and Magnetism
Topic
Lorentz Force
Idea tested
Radius-Momentum Proportionality

Same topic in other shifts

All Lorentz Force questions
  1. 2 Apr 2026, Shift 1 · Q481 μ1\ \muC charge moving with velocity v⃗=(i^−2j^+3k^)\vec v=\left(\hat i-2\hat j+3\hat k\right) m/s in the region of magnetic field…EasyNumerical value
  2. 2 Apr 2026, Shift 2 · Q29A particle having charge 10−910^{-9} C moving in xx-yy plane in fields of 0.4j^0.4\hat{j} N/C and 4×10−3k^4 \times 10^{-3}\hat{k} T experiences a…MediumSingle correct
  3. 5 Apr 2026, Shift 1 · Q49The charged particle moving in a uniform magnetic field of (3i^+2j^) T(3\hat{i} + 2\hat{j})\,\mathrm{T} has an acceleration…MediumNumerical value
  4. 5 Apr 2026, Shift 2 · Q38A particle of charge qq and mass mm is projected from origin with an initial velocity…MediumSingle correct
  5. 8 Apr 2026, Shift 2 · Q48A 5 mg particle carrying a charge of 5π×10−65\pi \times 10^{-6} C is moving with velocity of (3i^+2k^)×10−2\left(3\hat{i} + 2\hat{k}\right) \times 10^{-2}…MediumNumerical value
  6. 4 Apr 2025, Shift 2 · Q49A particle of charge 1.6 μ\muC and mass 16 μ\mug is present in a strong magnetic field of 6.28 T. The particle is then fired…EasyNumerical 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.