At a particular instant, a proton moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is
A) downward.
B) zero.
C) toward the south.
D) toward the north.
E) upward.

Question

Quizplus · Accepted Answer

The magnetic force on a charged particle moving in a magnetic field is given by the Lorentz force law, which is perpendicular to both the velocity of the particle and the magnetic field direction. Using the right-hand rule, with the proton moving east and the magnetic field directed downward, the force on the proton will be directed toward the north.

At a Particular Instant, a Proton Moves Toward the East