Ignition Coil: Description and Operation

The Ignition Coil uses the principle of mutual induction to step up battery (low) voltage to ignition (high) voltage. The Ignition Coil contains two windings of copper wire around a soft iron core. The primary winding is made of a hundred or so turns of wire. It is connected to the battery through the ignition switch. Current flows through it creating a magnetic field. When current flow in the primary winding is stopped (by the the igniter in the distributor interrupting circuit ground), the collapse of the magnetic field causes a voltage to be induced in the secondary windings. The ratio of turns in the primary windings to the number of turns in the secondary windings determines the voltage step up.