Question

A bar magnet of length 10 cm and having pole strength equal to ${10}^{-1}$ Wb is kept in a magnetic field. Then, the magnetic moment of the magnet is

• A. $\frac{10}{{\mu }_0}$
• B. $\frac{{10}^{-4}}{{\mu }_0}$
• C. $\frac{{\mu }_0}{10}$
• D. $\frac{{\mu }_0}{{10}^{-4}}$

Answer 1

The correct option is B $\frac{{10}^{-4}}{{\mu }_0}$

Magnetic moment of magnet
$M=m\times 2l$
Given, $l=10cm=0.1m,m=\frac{{10}^{-3}}{{\mu }_0}$
$\therefore M=\frac{{10}^{-3}}{{\mu }_0}\times 0.1=\frac{{10}^{-4}}{{\mu }_0}$