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A proton (mass m, charge e) enters a uniform magnetic field B perpendicular to its velocity v. Time to complete one full circle:
A2π m / (eB) (cyclotron period, independent of v)
B2π v / B
C2π / B
Dm v B
Answer & Solution
Correct answer: A. 2π m / (eB) (cyclotron period, independent of v)
T = 2π m / (qB). Notice that T is INDEPENDENT of velocity v and radius r. This is the cyclotron principle: charged particles in B field complete one circle in fixed time regardless of speed. Basis of cyclotron particle accelerators.
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