Question

An electron is moving perpendicular to a magnetic field of strength $0.55T$. Calculate the approximate time period of the electron in the field. Take the mass of the electron $m_e=9.1\times {10}^{-31}kg$ and its charge $e=1.6\times {10}^{-19}C$.

• A. $52\times {10}^{-12}s$
• B. $44\times {10}^{-3}s$
• C. $65\times {10}^{-12}s$
• D. $37\times {10}^{-9}s$

Answer 1

The correct option is C $65\times {10}^{-12}s$

Time period (T) of the electron moving perpendicular to a magnetic field of strength $B=0.55T$ would be
$T=\frac{2\pi m_e}{eB}$
Substituting the values of $m_e$, $e$ and B, we get $T=\frac{2\pi 9.1\times {10}^{-31}}{0.55\times 1.6\times {10}^{-19}}$
= 65 $\times {10}^{-12}s$.