There are two sets of coils, primary and secondary coils in the common ignition coil. The primary coil is used for a thicker wire, which is usually about 0.5-1 mm or so of the wire wound around 200-500. The secondary coil is coated with a thin wire, which is about 0.1 mm. One end of the primary coil is connected with a low voltage power supply (+) on the vehicle and the other end is connected with the switching device (off the appliance). One end of the secondary coil is connected with the primary coil, and the other end of the secondary coil is connected with the output terminal of the high voltage line.
The ignition coil is able to turn the low voltage into high voltage. It is because there is the same form as the ordinary transformer, the primary coil is larger than the secondary coil. However, the ignition coil is not the same as the ordinary transformer, the general transformer's operating frequency is fixed 50Hz, also known as the power frequency transformer, and the ignition coil is a pulse form, can be seen as a pulse transformer, it is based on different speed of the engine to the different frequency of storage and discharge.

When the primary coil is connected to the power supply, a strong magnetic field is generated around the current. The magnetic field can be stored in the core. When the switch device causes the primary coil circuit to be disconnected, the primary coil's magnetic field rapidly decays, and the secondary coil will produce a high voltage. The faster the magnetic field of the primary coil is, the greater the current of the current is broken, the greater the turn ratio of the two coils is, the higher the voltage is induced.

This paper is composed of  Renqiu High Voltage Wire Factory , finishing, more news and information: