how does an external resistor connect to ignition coil?

An external resistor connects to an ignition coil by being wired in series with the coil's primary winding. This resistor limits the current flowing to the coil, helping to prevent overheating and ensuring proper voltage levels for the ignition system. Typically, it is connected to the positive terminal of the coil and the ignition switch, while the other terminal of the coil connects to ground. This setup is common in older ignition systems to manage the power output effectively.