Select the best answer to each question. Note that a question and its answers may be split across a page break, so be sure that you have seen the entire question and all the answers before choosing an answer.
- The insulator of a typical spark plug is made of
A. porcelain.
B. oil-resistant fiberglass.
C. tempered steel.
D. soft plastic.
The Correct Answer and Explanation is :
The correct answer is A. porcelain.
Explanation:
Spark plugs are essential components in internal combustion engines, playing a critical role in igniting the air-fuel mixture within the engine’s combustion chamber. They create the spark that ignites the fuel-air mixture, allowing the engine to operate. The insulator of a spark plug is an integral part of its design, and it serves several functions.
The insulator is the part of the spark plug that surrounds the central electrode and prevents electrical contact between the electrode and the metal shell of the spark plug. It ensures that the electrical current flows only from the central electrode to the tip, where the spark is generated.
Porcelain is chosen as the material for the insulator due to its excellent electrical insulating properties, high heat resistance, and ability to withstand the intense conditions inside the engine. The high temperatures and pressures within an engine can exceed 450°C (850°F), and porcelain has a high melting point that makes it ideal for these extreme conditions. Additionally, porcelain is durable, resistant to electrical breakdown, and can withstand the mechanical stresses associated with engine vibrations.
Other materials listed in the options do not provide the same benefits as porcelain:
- B. oil-resistant fiberglass: While fiberglass is a strong material, it is not as effective in handling the extreme heat and electrical requirements that porcelain can manage.
- C. tempered steel: Steel is a conductive material, which would not be suitable for the insulator’s purpose of electrical insulation.
- D. soft plastic: Soft plastics do not offer the necessary heat resistance and mechanical strength required in the high-temperature environment of an engine.
In summary, the use of porcelain as the insulator in spark plugs is due to its combination of electrical insulation properties, durability under heat and pressure, and resistance to mechanical stress, which ensures the reliable performance of the spark plug in a combustion engine.