Helmholtz Coil Geometry


What does the equation B = 0.716 miu N I / r stands for? Is it only applied to Helmholtz? Why should it be 0.716?

What makes magnetic field uniform in a pair of Helmholtz coils?


I am not familiar with this equation. I suspect the 0.716 comes about due to the specific geometry of the Helmholtz arrangement. A Helmholtz coil is actually a pair of coils with the same axis, separated by a distance equal to their radius.

The field is only approximately uniform over a limited region of space. The spacing between coils and their diameter is arranged so that they tend to linearize each other's field.