The radius of a circular loop is $r$ and a current $i$ is flowing in it. The equivalent magnetic moment will be

Due to the flow of current in a circular loop of radius $R$,the magnetic field produced at the centre of the loop is $B$. The magnetic moment of the loop is

$A$ straight wire carrying current $i$ is turned into a circular loop. If the magnitude of the magnetic moment associated with it in $MKS$ units is $M$,the length of the wire will be

In a hydrogen atom,the electron is making $6.6 \times 10^{15} \text{ rev } s^{-1}$ around the nucleus in an orbit of radius $0.528 \text{ Å}$. The magnetic moment in $\text{A-m}^2$ is:

$A$ coil of $n$ turns and radius $R$ carries a current $I$. It is unwound and rewound to make a new coil of radius $\frac{R}{3}$ and the same current is passed through it. The ratio of the magnetic moment of the new coil to that of the original coil is

$A$ circular loop and a square loop are formed from two wires of same length and cross-section. The same current is passed through them. The ratio of their dipole moments is