Question

A $100$ turn closely wound circular coil of radius $10\,cm$ carries a current of $3.2\,A$ . The magnetic moment of the coil is, approximately

• A. $5\,A\,m^{2}$
• B. $10\,A\,m^{2}$
• C. $20\,A\,m^{2}$
• D. $40\,A\,m^{2}$

Answer 1

Answer: (B)

$10\,A\,m^{2}$

Answer 2

Magnetic moment,
$M=niA$
$M=100\times 3.2\times (\pi r_{1}^{2})$
$=100\times 3.2\times \frac{22}{7}\times \frac{10}{100}\times \frac{10}{100}$
$=10.048\,A-m^{2}$