It is one of only two producing foreign fields in China.

This is an operation on fields, that does not always produce a field.

In 1831, it was already known that an electric current produced a magnetic field.

It is often done to produce an electric field that extends out for a significant distance.

Part of that analysis includes measuring the electrical field produced by salt water in a person's head.

That eddy current produces a magnetic field of its own.

Why can a moving charge produce a magnetic field?

They are probably caused by electric fields produced above thunderstorms.

"I'm not sure it'll produce a strong enough field."

These organs produce a weak electric field that may function in communication.