Question

A negatively charged particle, falling freely under gravity, enters a region having uniform horizontal magnetic field, pointing towards north. The particle will be deflected towards -

• A. East
• B. West
• C. North
• D. South

Answer 1

The correct option is B West

Force experienced by a positively charged particle in an external magnetic field $\overrightarrow{B}$, moving with a velocity $\overrightarrow{v}$ is given by,

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

Therefore, the direction of the force $\overrightarrow{F}$ will be along $\overrightarrow{v}\times \overrightarrow{B}$.

Here, it is along the east.

But as the particle is negatively charged, it will experience a force directed towards the west because $\overrightarrow{F}=-q(\overrightarrow{v}\times \overrightarrow{B})$.

Hence, option $\left(B\right)$ is the correct answer.

Why this question? This question gives you understanding of the concept of force experienced by a charged particle in a uniform magnetic field.