Question

A charged particle of mass m and charge q travels on a circular path of radius r that is perpendicular to a magnetic field B.The time taken by the particle to complete one revolution is

• A. $\frac{2\pi qB}{m}$
• B. $\frac{2\pi q}{mB}$
• C. $\frac{2\pi m}{qB}$
• D. $\frac{qB}{2\pi m}$

Answer 1

The correct option is C $\frac{2\pi m}{qB}$

$\text{Solution}:$

Equating magnetic force to centripetal force,we get

$\frac{m{v}^2}{r}=qvBsin{90}^{\circ }$

Also,Time to complete one revolution is given by,

$T=\frac{2\pi r}{v}=\frac{2\pi m}{qB}$

$\text{Hence C is the correct option}$