Question

An electron is moving in a circular path under the influence of a transverse magnetic field of $3.57 \times 10^{-2} T$. If the value of $e / m$ is $1.76 \times 10^{11} C / kg$, the frequency of revolution of the electron is

• A. 1 GHz
• B. 100 MHz
• C. 62.8 MHz
• D. 6.28 MHz

Answer 1

Answer: (A)

1 GHz

Answer 2

$f = \frac{qB}{2\pi m}$
$= \left(\frac{q}{m}\right) . \frac{B}{2\pi}$
$= \frac{1.76 \times10^{11} \times3.57 \times10^{-2}}{2 \times3.14}$
$= 1 \times10^{9} Hz$
$= 1 \,GHz$