If a current of $15 \,A$ passes through a solenoid of length $25 \,cm$,radius $2 \,cm$ and number of turns $500$,then the magnetic moment of the solenoid is

Two particles each of mass $m$ and charge $q$ are attached to the two ends of a light rigid rod of length $2R$. The rod is rotated at a constant angular speed $\omega$ about a perpendicular axis passing through its centre. The ratio of the magnitudes of the magnetic moment of the system and its angular momentum about the centre of the rod is:

An electron in a circular orbit of radius $0.05 \ nm$ performs $10^{16}$ revolutions per second. The magnetic moment due to this rotation of the electron is (in $A \ m^{2}$):

$A$ wire of length $L$ $m$ carrying a current of $I$ $A$ is bent in the form of a circle. Its magnitude of magnetic moment will be

The magnetic moment of a circular coil carrying current is

The magnetic moments associated with two closely wound circular coils $A$ and $B$ of radius $r_A = 10 \ cm$ and $r_B = 20 \ cm$ respectively are equal if: (Where $N_A, I_A$ and $N_B, I_B$ are the number of turns and current of $A$ and $B$ respectively)