An electron has an initial velocity to the south but is observed to curve upward as the result of a magnetic field.This magnetic field must have a component
A)to the west.
B)to the east.
C)upward.
D)downward.
E)to the north.

Question

Quizplus · Accepted Answer

The magnetic force on a moving electron is given by the Lorentz force equation: F = qvB sin(theta), where q is the charge of the electron, v is its velocity, B is the magnetic field strength, and theta is the angle between v and B. In this case, the electron is moving to the south, so v is in the negative y-direction. The magnetic field must have a component to the west, so B is in the negative x-direction. The cross product of v and B is in the positive z-direction, so the electron will curve upward.

An Electron Has an Initial Velocity to the South but Is