The value of the electromotive force (EMF) induced by an alternator depends on the strength of the magnetic field. Increasing the strength of the magnetic field, increases the value of the induced EMF.
It also depends on the speed at which the magnet rotates, and on the number of turns of wire on the stationary coil.
A single phase model has only 1 stationary coil. In a real automobile alternator, 3 separate coils of wire, or phase windings are common. The windings are arranged so that when the magnet is rotated, it generates a 3-phase output. The phases are equally spaced in time, and this results in a phase shift of 120 degrees.
An alternating current (AC) is an electrical current where the magnitude and direction of the current varies cyclically, as opposed to direct current, where the direction of the current stays constant. The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of energy. However in certain applications different waveforms are used, such as triangular or square waves.
Used generically, AC refers to the form in which electricity is delivered to businesses and residences. However, audio and radio signals carried on electrical wire are also examples of alternating current. In these applications, an important goal is often the recovery of information encoded (or modulated) onto the AC signal.
