Question

An electron having mass m and kinetic energy E enter in uniform magnetic field B perpendicularly, then its frequency will be

• A. $\frac{ eE}{ qvB}$
• B. $\frac{ 2 \pi m}{ e B}$
• C. $\frac{ eB}{2 \pi m }$
• D. $\frac{ 2 m }{ e B E }$

Answer 1

Answer: (C)

$\frac{ eB}{2 \pi m }$

Answer 2

The frequency of revolution of charged particle
in a perpendicular magnetic field is
$\upsilon = \frac{1}{T} = \frac{ 1}{ 2 \pi r /v }$
$= \frac{ v}{ 2\pi r} = \frac{v}{2 \pi } \times \frac{ e B }{mv }$
$= \frac{eB}{2 \pi m }$.