Electromagnetism
Magnetic fields are generated by moving charges (electrical current) The direction of the magnetic field can either be clockwise or counter-clockwise with respect to the direction of flow of the current. Ampere’s law or Fleming’s Right hand rule determines the magnitude and direction of the magnetic field due to a current; if you point your right hand thumb along the direction of the current, then the magnetic field points along the direction of the curled fingers. Just as moving electrical charge generates magnetic fields, changing magnetic fields generate electric currents. When a magnet is moved in and out of a closed circuit, an oscillating current is produced whichceases the moment the magnet stops moving. Such a current is called an induced electric current. Faraday’s law of induction explains the phenomenon of an induced current. The change of magnetic flux through a closed circuit induces an electromotive force (emf) in the circuit. The emf drives a current in the circuit and is the result of a changing magnetic field inducing an electric field.