Question

Which particle will have minimum frequency of revolution when projected with the same velocity perpendicular to a magnetic field?

• A. $L{i}^{+}$
• B. Electron
• C. Proton
• D. $H{e}^{+}$

Answer 1

The correct option is A $L{i}^{+}$

Frequency of revolution,

$f=\frac{1}{T}$

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

$m=$ mass of charged particle

$q=$ charge on particle

$f=\frac{qB}{2\pi m}$, $B=$ magnetic filed

$\because L{i}^{+}$, electron, proton and $H{e}^{+}$ have same magnitude of charge.

$\therefore f\propto \frac{1}{m}$

$\therefore f_{min}$ will occur for a particle with maximum mass.

$L{i}^{+}$has maximum mass among the given particles.

$L{i}^{+}$will have minimum frequency.

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