Question

An electron is travelling along the x-direction. It encounters a magnetic field in the ydirection. Its subsequent motion will be

• A. straight line along the x-direction
• B. a circle in the zx-plane
• C. a circle in the yz-plane
• D. a circle in the xy-plane

Answer 1

The correct option is B a circle in the zx-plane

The magnetic force acting on a charged particle is given by

$\overrightarrow{F}=q(\overrightarrow{v}\times \overrightarrow{B})$

Hence direction of force acting one electron is $\hat{i}\times \hat{j}=\hat{k}$

The force experienced is in z-direction. So the particle moves in the zx plane.