Write the equation of the magnetic dipole moment in terms of electric current.

$A$ thin disc of radius $R$ and mass $M$ has charge $q$ uniformly distributed on it. It rotates with angular velocity $\omega$. The ratio of magnetic moment and angular momentum for the disc is

The magnitude of magnetic induction at a point on the axis at a large distance $(r)$ from the centre of a circular coil of $n$ turns and area $A$ carrying current $I$ is given by:

$A$ circular coil of radius $4\, cm$ and of $20$ turns carries a current of $3$ amperes. It is placed in a magnetic field of intensity $0.5\, Wb/m^2$. The magnetic dipole moment of the coil is.......$A \cdot m^2$.

An insulating thin rod of length $l$ has a linear charge density $\rho(x) = \rho_0 \frac{x}{l}$ on it. The rod is rotated about an axis passing through the origin $(x = 0)$ and perpendicular to the rod. If the rod makes $n$ rotations per second,then the time-averaged magnetic moment of the rod is:

$A$ uniform conducting wire of length $24a$ and resistance $R$ is wound up as a current-carrying coil in the shape of an equilateral triangle of side $a$ and then in the form of a square of side $a$. The coil is connected to a voltage source $V_{0}$. The ratio of the magnetic moment of the coils in the case of the equilateral triangle to that of the square is $1 : \sqrt{y}$, where $y$ is ..... .