A charged particle is moving in a region where the magnetic field strength is 1.0 T directed in the +x direction and the electric field is 1500 V/m in the +y direction. The particle velocity required for a straight-line trajectory is
A) 15 km/s.
B) 2500 m/s.
C) 1500 m/s.
D) No velocity will produce a straight-line trajectory.

Question

Quizplus · Accepted Answer

The electric force on the particle is qE, where q is the charge of the particle and E is the electric field strength. The magnetic force on the particle is qvB, where v is the velocity of the particle and B is the magnetic field strength. For a straight-line trajectory, the electric force and the magnetic force must be equal and opposite. Therefore, qE = qvB, or v = E/B. Substituting the given values, we get v = 1500 V/m / 1.0 T = 1500 m/s.

A Charged Particle Is Moving in a Region Where the Magnetic