# 16.(a) For a circular coil of radius R and N turns carrying current I, the magnitude of the magnetic field at a point on its axis at a distance x from its centre is given by,         $B = \frac{\mu _0 IR^2N}{2 ( x^2 + R^2 )^{3/2}}$ Show that this reduces to the familiar result for the field at the centre of the coil.

$B = \frac{\mu _0 IR^2N}{2 ( x^2 + R^2 )^{3/2}}$
$B = \frac{\mu _0 IN}{2R}$