Question

An electron and a proton enters into a region of uniform magnetic field at right angles to the field with the same kinetic energy. They describe circular paths of radius $r_e$ and $r_p$ respectively. then-

Answer 1

Radius of the circular path followed by the charge particles in the magnetic field is,

$r=\frac{mv}{qB}=\frac{P}{qB}=\frac{\sqrt{2m{E}_k}}{qB}$

Since, $KE$ of the particles is same.

$\Rightarrow r\propto \frac{\sqrt{m}}{q}$

As $q_e=q_p=e$ and $m_p>m_e$

$\Rightarrow r_p>r_e$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(B\right)$ is the correct answer.