Question

An electron is moving along the positive x-axis. You want to apply a magnetic field for a short time so that the electron may reverse its direction and move parallel to the nagative x-axis. This can be done by applying the magnetic field along
A. y-axis
B. z-axis
C. y-axis only
D. z-axis only

Answer 1

Correct Answer - (a,b)
Use right hand rule or `vecF=qvecvxxvecB` for explanation.

If we apply magnetic field along y-direction, teh circular path in
x-z plane, the particle can move parallel to magnetic direction.
If we apply the magnetic field in z-direction, the plane of circular
path will be x-y plane.