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Friday, 9 October

JEE Main 2026 · PhysicsMultiple choiceSingle correctMediumApplication

JEE Main 5 April 2026, Shift 2, Physics Q38

Question 38 of 75 in this shift, Physics question 13 of 25, Section A.

A particle of charge qq and mass mm is projected from origin with an initial velocity v⃗=(v02x^+v02y^)\vec{v}=\left(\frac{v_0}{\sqrt{2}}\hat{x}+\frac{v_0}{\sqrt{2}}\hat{y}\right). There exists a uniform magnetic field B⃗=B0z^\vec{B}=B_0\hat{z} and a space varying electric field E⃗=E0 e−λxx^\vec{E}=E_0\,e^{-\lambda x}\hat{x} within the region 0≤x≤L0\leq x\leq L. After travelling a distance such that xx-coordinate has changed from x=0x=0 to x=Lx=L, the change in the kinetic energy is __________.
  1. (1)qE0λ[1−e−λL]\frac{qE_0}{\lambda}\left[1-e^{-\lambda L}\right]Official answer
  2. (2)(v0qB02λ)[2−e−2λL]\left(\frac{v_0 q B_0}{2\lambda}\right)\left[2-e^{-2\lambda L}\right]
  3. (3)qE0λ[1+e−λL]\frac{qE_0}{\lambda}\left[1+e^{-\lambda L}\right]
  4. (4)q(E0+v0B0λ)[1−e−λL/2]q\left(\frac{E_0+v_0B_0}{\lambda}\right)\left[1-e^{-\lambda L/2}\right]

Official answer

Option 1

NTA final key.

Chapter
Moving Charges and Magnetism
Topic
Lorentz Force
Idea tested
Kinetic Energy Change in Combined E and B Fields

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. 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
  5. 3 Apr 2025, Shift 2 · Q40Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A : If Oxygen ion…MediumAssertion–reason
  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.