| A spark plug is an electrical device used to ignite | | | | This plug as discussed above is connected to the |
| compressed aerosol gasoline by means of an | | | | high-voltage brought upon by the ignition coil or |
| electric spark, as its name suggests. It is usually | | | | magneto. The electrons flow from the foil and |
| found in the cylinder head of some internal | | | | thus a difference in voltage develops between the |
| combustion engines. These plugs have an insulated | | | | center and side electrodes. The current still |
| center electrode which is connected by also a | | | | wouldn't be able to flow here as the fuel and air in |
| heavily insulated wire to an ignition coil or magneto | | | | the gap is an insulator. However, as the high |
| circuit on the outside. This then forms, along with | | | | voltage rises further, the gases located between |
| a grounded terminal on the base of the plug, a | | | | the electrodes change structure. And when the |
| spark gap inside the cylinder. Only some of the | | | | voltage exceeds the dielectric strength of the |
| internal combustion engines use spark plugs(and | | | | gases, the gases become ionized. This will then be |
| these are called spark-ignition engines) because | | | | the conductor for the electrons to be able to flow |
| others use compression-ignition engine like that of | | | | through the gap. |
| diesel engines. | | | | |