Magnetic force on a moving charge
A charged particle moves through a uniform magnetic field, perpendicular to the field lines. The magnetic force on it:
Answer D: explanation for every choice
A
A force perpendicular to motion cannot change speed.
B
The magnetic force is perpendicular to both the velocity and the field.
C
The force is zero only when the particle moves parallel to the field.
D
Correct. F = qvB sin θ is always perpendicular to the velocity, so it does no work and produces circular motion.
TakeawayThe magnetic force is perpendicular to velocity, so it does no work.
Equation usedMagnetic force on a moving charge
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