Chapter 28, Problem 61GP

(a)

To determine

The magnetic field at points x along the line joining their centers.

(b)

To determine

Show that the field midway between the coils is particularly uniform by showing that $\frac{dB}{dx}=0$ and $\frac{d^{2}B}{d{x}^2}$ is zero at the midpoint between the coils.

(c)

To determine

The field at the midpoint between the coils $x=\frac{R}{2}$.