A positively charged particle moves with velocity v along the x axis. A uniform magnetic field -B exists in the negative z direction. You want to balance the magnetic force with an electric field so that the particle will continue along a straight line. The electric field should be in the
A) positive x direction.
B) positive z direction.
C) negative y direction.
D) negative x direction.
E) negative z direction.

Question

A positively charged particle moves with velocity v  along the x axis. A uniform magnetic field -B  exists in the negative z direction. You want to balance the magnetic force with an electric field so that the particle will continue along a straight line. The electric field should be in the
A) positive x direction. 
B) positive z direction. 
C) negative y direction. 
D) negative x direction. 
E) negative z direction.

Quizplus · Accepted Answer

The magnetic force on a charged particle moving in a magnetic field is given by F = q(v x B), where q is the charge, v is the velocity, and B is the magnetic field. In this case, the magnetic force is given by F = qvB in the negative y direction.

To balance this force with an electric field, we need an electric force in the positive y direction, which can be achieved with an electric field in the negative y direction according to F = qE. Therefore, the correct answer is option C.

A Positively Charged Particle Moves with Velocity V Along