Question

A proton traveling with speed v enters a uniform electric field of magnitude E, directed parallel to the plane of the page, as shown in the figure. There is also a magnetic force on the proton that is in the direction opposite to that of the electric force.

Which of the following is a possible direction for the magnetic field?

Answer 1

The correct option is: (D)

Explanation:

The electric force would act upwards on the proton so the magnetic force would act down. Using RHRflat, the B field must point out of the page.