Magnetic Field of Toroid

Finding the magnetic field inside a toroid is a good example of the power of Ampere's law. The current enclosed by the dashed line is just the number of loops times the current in each loop. Amperes law then gives the magnetic field by
The toroid is a useful device used in everything from tape heads to tokamaks.

Magnetic field = permeability x turn density x current
The Earth's magnetic field is about half a gauss.
The relative permeability of magnetic iron is around 200.
Enter data, then click on the quantity you wish to calculate in the active formula above the illustration. Default values will be entered for unspecified parameters, but the numbers will not be forced to be consistent until you click on the quantity to calculate.
