This definition will eventually be replaced by just 'so many electron charges per second'. New technology allows single electrons to be counted. Ampere's Law provides an alternative formulation of the relation between a magnetic field and its sources. In fact, this is the integral form of the Biot-Savart Law. Examples of Ampere's law Now suppose several long, straight conductors pass through the surface bounded by the integration path.
Charges moving in the magnetic field cause a force opposing motion.
The induced current is always in a direction such that the change in flux caused by it opposes the change in flux that produces it. These are undesirable in transformers and motors as they dissipate energy, but they have many practical uses. Engineering applications - this generator produces an AC voltage and can efficiently transform mechanical energy into electrical energy. A constant magnetic field exists, the resistance in the U-shaped wire is constant R and the mass of the rod is m . Find the magnetic retarding force F m on the rod.