Question

An electron is revolving around a proton producing a magnetic field of $16 Wb / m ^{2}$ in circular orbit of radius $1 \mathring{A}$. Its angular velocity will be

• A. $10^{17} rad / sec$
• B. $1 / 2 \pi \times 10^{12} rad / sec$
• C. $2 \pi \times 10^{12} rad / sec$
• D. $4 \pi \times 10^{12} rad / sec$

Answer 1

Answer: (A)

Magnetic field due to revolution of electron
$B =\frac{\mu_{ o }}{4 \pi} \times \frac{2 \pi I }{ r }=\frac{\mu_{ o }}{4 \pi} \times \frac{2 \pi}{ r }\left(\frac{ e \omega}{2 \pi}\right)$
$B=10^{-7} \times \frac{e \omega}{r}$
$16=10^{-7} \times \frac{1.6 \times 10^{-19} \times \omega}{1 \times 10^{-10}}$
$\omega=10^{17} rad / sec$