If an electron moves in a magnetic field,
A) it always feels a force.
B) it only feels a force if its velocity vector is parallel (or antiparallel) to the direction of the magnetic field.
C) it only feels a force if its velocity vector is not parallel (or antiparallel) to the direction of the magnetic field.
D) it does not feel a force if it is in motion, only if stationary.

Question

Quizplus · Accepted Answer

The force on an electron moving in a magnetic field is given by the Lorentz force law, which states that the force is proportional to the cross product of the velocity of the electron and the magnetic field. This means that the electron only feels a force if its velocity vector is perpendicular to the magnetic field direction. If the velocity is parallel or antiparallel to the magnetic field, the cross product is zero, and no force is experienced.

If an Electron Moves in a Magnetic Field