Physics - Magnetism Question with Solution | TestHub

A coil of radius $r$ carrying current $I$, magnetic field at a point at a distance $R$ from the centre of the coil is given by $B=\frac{{\mu }_{0}I{r}^2}{2{\left[R^2+r^2\right]}^{3/2}}$ At the centre of a coil, $R=0$ $\therefore B=\frac{{\mu }_{0}I{r}^2}{2r^3}=\frac{{\mu }_{0}I}{2r}$