Question

Can an electric or a magnetic field, each constant in space and time, be used to accomplish the actions described below? Explain your answers. Indicate if the answer is valid for any orientation of the field(s). Must any other condition be satisfied?

(a) move a charged particle in a circle;

(b) exert a force on a piece of dielectric;

(c) increase the speed of a charged particle;

(d) accelerate a moving charged particle;

(e) exert a force on an electron initially at rest.

Answer 1

(a) move a charged particle in a circle;

This case, cannot accomplish. If electric field is consnat, the particle should move in one direction, not in multiple directions at any instant of time

(b) exert a force on a piece of dielectric;

This case, cannot accomplish. If force exert on dielectric on a side, then equal and opposite forces are generate on either side, results in zero net force, that is net zero field

(c) increase the speed of a charged particle;

The direction of particle only changed by magnetic field, not speed. However, the electric field can change the speed because it exerts a force along itself.

(d) accelerate a moving charged particle;

Both can accelerate a moving charged particle. Magnetic field produces rotational acceleration, whereas electric field can change direction and velcoity also

(e) exert a force on an electron initially at rest.

Only an electric field can exert a force on a charge at rest. After a charge is set in motion by electric field, it experice magnetic field.