Due to the flow of current in a circular loop of radius $R$,the magnetic induction produced at the centre of the loop is $B$. The magnetic moment of the loop is (where ${\mu _0}$ is the permeability constant).

$A$ steady current $i$ flows in a small square loop of wire of side $L$ in a horizontal plane. The loop is now folded about its middle such that half of it lies in a vertical plane. Let $\overrightarrow {{\mu _1}} $ and $\overrightarrow {{\mu _2}} $ respectively denote the magnetic moments due to the current loop before and after folding. Then

$A$ conducting solid sphere of radius $R$ and mass $M$ carries a charge $Q$. The sphere is rotating about an axis passing through its center with a uniform angular speed $\omega$. The ratio of the magnitudes of the magnetic dipole moment to the angular momentum about the same axis is given as $\alpha \frac{Q}{2 M}$. The value of $\alpha$ is $....$ .

$A$ circular coil of diameter $7\,cm$ has $24$ turns of wire carrying a current of $0.75\,A$. The magnetic moment of the coil is

In a hydrogen atom,the electron moves around the nucleus in an orbit of radius $5 \times 10^{-11} \ m$. Its time period is $1.5 \times 10^{-16} \ s$. The current associated with the electron motion is $........$ (charge of electron is $1.6 \times 10^{-19} \ C$)

The dimensional formula for magnetic moment is: