Question

A positively charged particle of charge $q$ is moving in circular path of radius $r$ within uniform magnetic field, $B$. Find the expression which gives the magnitude of the particle's linear momentum.

• A. $qBr$
• B. $\frac{qB}{r}$
• C. $\frac{q}{\left(Br\right)}$
• D. $\frac{B}{\left(qr\right)}$
• E. $\frac{r}{\left(qB\right)}$

Answer 1

The correct option is A $qBr$

Here the centripetal force will balance the magnetic force.

So, $m{v}^2/r=qvB$

or $mv=qBr$

Thus, linear momentum, $p=mv=qBr$