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Question 20228
JEE Physics · Hard

Magnetism: Moving Charge — Helical Pitch MCQ

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Moving Charge — Helical PitchHardQuestion 20228

Question

A proton enters a magnetic field B at angle 30° to the field direction with speed v. The pitch of the resulting helix is:
  1. A
    πmv sin30°/qB
  2. B
    2πmv cos30°/qB
    Correct
  3. C
    πmv cos30°/qB
  4. D
    2πmv sin30°/qB

Correct answer

2πmv cos30°/qB

Explanation

The component parallel to B is v‖ = v cos30°. Pitch = v‖ × T = v cos30° × (2πm/qB) = 2πmv cos30°/(qB).

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