Next: A long straight wire
Previous: Torque on a Current
When we introduced the electric field it was apparent that electric
charges were the source of such a field. Experiments in the 19th century
showed that the source of a magnetic field was a moving charge,
or current. A detailed mathematical relation between a
charge moving at velocity and the associated magnetic field
is known as Ampère's law or, in another form, the Biot-Savart law.
We will consider three special cases of the results of this law.