What produces a magnetic field?

A current flowing through a conductor produces a magnetic field due to the relationship defined by Ampère's Law, which states that electric currents create circular magnetic fields around themselves. When an electric charge moves through a conductor—such as a wire—it generates a magnetic field that can be detected with a compass or measured with instruments like a magnetometer.

This principle is fundamental to many technologies, including electromagnets, motors, and generators. The direction of the magnetic field produced is determined by the right-hand rule, where placing your right thumb in the direction of the current flow allows your fingers to curl in the direction of the magnetic field lines.

While static charges can create electric fields, they do not create magnetic fields unless there is movement involved. Similarly, magnetic materials themselves display magnetic properties but do not inherently produce magnetic fields without being influenced by other magnetic fields or currents. Electrical resistance does not generate a magnetic field; rather, it refers to the opposition to current flow within a conductor, typically resulting in heat rather than the creation of magnetic fields.