Question

In uniform circular motion of a charged particle in a magnetic field, the magnetic force \[F = qvB\] acts as which of the following?

Options

• A frictional force that gradually reduces the particle's kinetic energy

• A tangential force that increases the particle's speed

• A centripetal force directed perpendicular to \[\vec v\] at every instant

• A restoring force proportional to displacement from equilibrium

Answer 1

When \[\vec v\] is perpendicular to \[\vec B\], the magnetic force F = qvB acts perpendicular to \[\vec v\] at every instant, exactly like a centripetal force. The particle is continuously deflected without gaining or losing speed, resulting in uniform circular motion.