Question

A charged particle enters a magnetic field \[\vec B\] with velocity \[\vec v\] such that the angle between them is 90°. What type of path does the particle follow?

Options

• A helical path along the direction of \[\vec B\]

• A straight line along the direction of \[\vec B\]

• A uniform circular motion in the plane perpendicular to \[\vec B\]

• A parabolic path in the plane perpendicular to \[\vec B\]

Answer 1

When velocity \[\vec v\] is perpendicular to the magnetic field \[\vec B\] (θ = 90°), 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.