Which component is NOT part of a spark plug?

The ignition coil is not a component of a spark plug. Instead, it is a separate part of the ignition system that converts the battery's low voltage into the high voltage needed to create a spark at the spark plug. The role of the ignition coil is crucial in starting the engine and ensuring it runs smoothly, but it does not physically constitute any part of the spark plug itself.

In contrast, the spark plug comprises several key components that work together to ignite the air/fuel mixture in the engine's combustion chamber. The electrode is essential for conducting electricity and is where the spark forms to ignite the mixture. The terminal nut is used for connecting the spark plug to the ignition system, allowing for the transfer of electrical energy. Lastly, the ceramic insulator protects the conductive parts of the spark plug and provides dielectric strength, preventing unwanted electrical leakage. These components make up the spark plug’s construction, while the ignition coil operates in conjunction with the spark plug to ensure engine functionality.