How Spark Plugs Work

Under the action of high voltage, the air between the central electrode and the side electrode of the spark plug will rapidly ionize, forming positively charged ions and negatively charged free electrons. When the voltage between the electrodes reaches a certain value, the number of ions and electrons in the gas increases like an avalanche, causing the air to lose its insulation, and the gap forms a discharge channel, causing the "breakdown" phenomenon to occur. At this time, the gas forms a light-emitting body, that is, "spark". As it expands under heat, a "pop" sound also occurs. The temperature of this electric spark can be as high as 2000-3000℃, which is enough to ignite the mixture in the combustion chamber of the cylinder .