Choosing the correct ignition coil.The Flame Thrower 40,000V coils have internal resistance rated at 1.5 or 3.0 ohms. The 3.0-ohm coil should be used on PerTronix Ignitors installed on four- and ...

Just how does an ignition coil work to step up a battery's 12 volts (even less with a ballast resistor) to the tens of thousands of volts needed to fire the spark plugs?