The ratio of the magnetic field at the centre of a current-carrying circular loop to its magnetic moment is '$x$'. When both the current and the radius are tripled, the new ratio will be:

The magnetic field at the centre of a current carrying circular coil of an area $A$ is $B$. The magnetic moment of the coil is (where $\mu_0$ is the permeability of free space).

The magnetic moment of a current $(i)$ carrying circular coil of radius $(r)$ and number of turns $(n)$ varies as

$A$ current loop placed in a magnetic field behaves like a

$A$ circular loop and a square loop are formed from the same wire and the same current is passed through them. Find the ratio of their dipole moments.

$A$ uniform conducting wire of length $12 a$ and resistance $R$ is wound up as a current-carrying coil in the shape of,
$(i)$ an equilateral triangle of side $a$.
$(ii)$ a square of side $a$.
The magnetic dipole moments of the coil in each case respectively are: