What is difference between an Alternator and a Generator?
In a generator, an armature is spun inside a magnetic field. The
armature consists of several coils which generate electrical energy
as they spin through the magnetic fields. "Brushes" (electrical
devices to transfer the electrical energy from the moving armature)
conduct the electrical energy to a wire. The strength of the
electrical output can be controlled by varying the strength of the
stationary magnetic field that is OUTSIDE the spinning armature. If
that magnetic field is to be changed, it typically must be an
An ALTERNATOR is exatly the opposite. The brushes make contact
with two spinning rings. The rings are connected to coils, and when
voltage is applied the armature (in the case of an alternator it is
called a "rotor") becomes a spinning electromagnet. A stationary
coil or set of coils, depending on the complexity of the armature,
generates electrical current as the magnets pass by.
An alternator produces "alternating current" electricity which
must be converted to "direct current" in the case of automobiles.
The conversion is relatively simple, using what is called a "diode
plate", which is as the name suggests, a collection of diodes.