Question

A circular coil of radius 5x10^-2m and with 40 turns is carrying a current of 0.25 A. determine the magnetic field of the circular coil at the center.

Answer 1

The magnetic field at the center of circular coil

$$B=\frac{\mu_0 N I}{2\pi r}$$

$$B=\frac{4\pi*10^{-7}*40*0.25}{2\pi*5*10^{-2}}=4*10^{-5}\:\rm T$$