Question

Imaging that an electron revolves around a circle of the radius $5.3\times 10^{- 11} \, m$ with a linear speed of $7.5 \, \times 10^{4} \, m \, s^{- 1}$ in a hydrogen atom. The magnetic field produced at the centre of the circle, due to the electron, is

• A. $43 \, Wbm^{- 2}$
• B. $4300 \, Wbm^{- 2}$
• C. $0.43 \, Wb \, m^{- 2}$
• D. $43\times 10^{- 4} \, Wbm^{- 2}$

Answer 1

Answer: (C)

$B=\frac{\mu _{0}}{4 \pi }\frac{e v}{r^{2}}$
$=\frac{10^{-7} \times 1.6 \times 10^{-19} \times 7.5 \times 10^{+4}}{\left(5.3 \times 10^{-11}\right)^2}$
On solving, $B=0.43 \, \, Wb \, m^{- 2}$