The working principle of the spark plug

Under the action of high voltage(spark plug), the air between the central electrode and the side electrode of the spark plug will ionize rapidly, forming positively charged ions and negatively charged free electrons(spark plug). When the voltage between electrodes reaches a certain value, the number of ions and electrons in the gas increases like an avalanche, so that the air loses its insulation, and the gap forms a discharge channel and "breakdown" phenomenon. At this time, the gas forms a luminous body, that is, a "spark". With its thermal expansion, it also makes a "pop" sound. The temperature of this electric spark can be as high as 2000 ~ 3000 ℃, which is enough to ignite the mixture in the cylinder combustion chamber.(spark plug)