Question

What is the direction of magnetic force on the negatively charged particle $q$ which is moving in the magnetic field of a long current carrying wire, as shown in the figure?

• A. Left
• B. Right
• C. Upward
• D. Downward

Answer 1

The correct option is A Left

By using the right-hand thumb rule, we find the direction of the magnetic field $\overrightarrow{B}$ due to the long current carrying wire, which is shown in the figure.



From the given information we can take the direction of $\overrightarrow{v}$ and $\overrightarrow{B}$ as $\hat{v}=\hat{j}$ and $\hat{B}=\hat{k}$ respectively.

Now, the direction of magnetic force on a charged particle is,

$\widehat{F_m}=\hat{v}\times \hat{B}=\hat{j}\times \hat{k}=\hat{i}$

As the particle is negatively charged, so the direction of $\overrightarrow{F}$ will be towards the Left.