An electron is moving along positive x-axis. To get it moving on an anticlockwise circular path in x-y plane, a magnetic field is applied

Options

A. Along positive y-axis
B. Along positive z-axis
C. Along negative y-axis
D. Along negative z-axis

Answer

B

Explanation

To move the electron in xy plane, force on it must be acting in the y-direction intially. The direction of vecF is known, and the direction of v is known, hence by applying Fleming's left hand rule, the direction of magnetic field is also determined.