Question

An electron in a circular orbit of radius $0.5A^o$ makes $7\times {10}^{15}$ revolutions in each second. This electron orbit is equivalent to a magnetic shell of moment (in Am):

• A. $88\times {10}^{-25}$
• B. $8.89\times {10}^{-25}$
• C. $44\times {10}^{-25}$
• D. $4.4\times {10}^{-25}$

Answer 1

Answer: (B)

$8.89\times {10}^{-25}$

$M=\frac{A{r}^{2}e}{T}$
$T=\frac{1}{f}$
$⟹M=A{\pi }^{2}ef$
$=A\times (0.5{)}^2\times 1.6\times {10}^{-19}\times 7\times {10}^{15}$
$=8.79\times {10}^{-25}$
$=8.8\times {10}^{-25}$