The process of generating a high-voltage spark by the ignition electrode involves a series of physical and electrical principles. Here is a detailed explanation:

1. The function of the ignition coil The ignition coil acts as a step-up transformer, converting the low voltage (typically 12V or 24V) from the battery to a high voltage (ranging from several thousand to tens of thousands of volts). This conversion is achieved through electromagnetic induction. Inside the ignition coil, there are primary and secondary windings. When the current in the primary winding is suddenly cut off, electromagnetic induction causes a very high induced electromotive force in the secondary winding, resulting in a high voltage.

2. Generation of high voltage In the car ignition system, the ignition coil can boost the 12V low voltage to a high voltage of 20,000V to 30,000V. This high voltage is necessary to break down the air in the gap between the spark plug and the fuel-air mixture, creating an electric spark that ignites the fuel.

3. Formation of the electric spark When the high voltage generated by the ignition coil is transmitted to the spark plug via the high-voltage wire, a strong electric field forms between the two electrodes of the spark plug. As the voltage continues to rise, it eventually ionizes the gas molecules between the electrodes, forming a conductive path and producing an electric spark. This process is known as 'breakdown.'

4. Working principle of the electric spark According to the principle of electric spark generation, when a certain voltage ionizes the air or other substances between the electrodes, it is released as a spark. This ionization process requires a sufficiently high voltage to overcome the insulating properties of the medium between the electrodes, thus forming a visible electric spark. The energy generated by the friction between stones can also produce an electric spark.

However, this is due to the heat generated by the friction, which causes localized high temperatures and results in a glow, not a true electric arc. In summary, the ignition electrode uses the ignition coil to boost low voltage to high voltage, and then uses this high voltage to generate an electric spark between the spark plug electrodes, igniting the fuel mixture inside the engine, thus completing the ignition process.