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A charged particle of charge q, mass m enters magnetic field B perpendicular to velocity v. It follows a:
AStraight line
BCircular path of radius mv/(qB)
CParabola
DSpiral
Answer & Solution
Correct answer: B. Circular path of radius mv/(qB)
Magnetic force provides centripetal force: qvB = mv²/r → r = mv/(qB). Circular motion with no change in speed (B does no work). Period T = 2π m/(qB) — independent of velocity.
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