What is the primary purpose of a spark plug in a gasoline engine?

• A. Ignite the air in the cylinder
• B. Warm the cylinder of a diesel engine
• C. Ignite the fuel air mixture in a gasoline engine
• D. Lower the ignition point of the fuel

Answer: (C)

The spark plug’s job is to provide a controlled spark that ignites the fuel-air mixture in the cylinder at the right moment. This ignition starts the combustion process, creating the pressure that pushes the piston and drives the engine. It’s not used to ignite only air, it doesn’t warm the cylinder, and it doesn’t lower the fuel’s ignition point—the mixture’s ignition is achieved by the spark at the correct timing.