Spark plug facts for kids

A spark plug, sometimes called a "sparking plug," is a special device that helps engines work. It delivers an electric spark to light up the mix of air and fuel inside an engine's combustion chamber. This spark is what makes the engine run!

How a Spark Plug Works

A spark plug is connected to something called an ignition coil. This coil creates a lot of electricity. When this electricity flows through the coil, a big difference in electric power builds up between two parts of the spark plug called electrodes.

Creating the Spark

When the electric power difference is strong enough, the electricity jumps across a small gap between the electrodes. This jump creates a very hot, bright spark! This spark is super important because it ignites, or sets on fire, the air and fuel mixture.

What Happens Next

Once the air and fuel mixture catches fire, it expands very quickly. This expansion pushes a part of the engine called a piston. The movement of the piston is what makes the engine turn and power the vehicle or machine.

Parts of a Spark Plug

Spark plugs might look simple, but they have several important parts that work together.

Insulator

The main body of a spark plug is often made from a strong ceramic material, like alumina. This part is called the insulator. Its job is to stop the electricity from going where it shouldn't. It keeps the high voltage focused on the electrodes.

Electrodes

Every spark plug has at least two electrodes:

• Central electrode: This is usually a thin rod in the middle of the spark plug.
• Side (or ground) electrode: This is a small piece of metal that bends over the central electrode, creating the gap where the spark jumps. Some spark plugs even have two or more side electrodes!

Gap Size

The small space between the central and side electrodes is called the "gap." The size of this gap is very important. If it's too big or too small, the spark plug might not work correctly. Mechanics use a special tool called a gap gauge to check and adjust this distance.

Why Spark Plugs are Important

Without working spark plugs, an engine can't start or run smoothly. They are essential for:

• Starting the engine: The first spark is needed to get the engine going.
• Keeping the engine running: Sparks are needed continuously as the engine operates.
• Fuel efficiency: Good spark plugs help the engine burn fuel efficiently, saving gas.
• Reducing pollution: A proper burn means less harmful stuff comes out of the exhaust.

When to Change Spark Plugs

Over time, spark plugs can wear out. The electrodes can get dirty or worn down, making the spark weaker. When this happens, an engine might:

• Run roughly
• Use more fuel
• Have trouble starting

It's a good idea to change spark plugs regularly, usually every few years or after a certain number of miles, as recommended by the vehicle's manufacturer. Replacing old spark plugs with new ones can make a big difference in how well an engine performs!

Images for kids

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  Dissected modern spark plug showing the one-piece sintered alumina insulator. The lower portion is unglazed.

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  Two spark plugs in comparison views in multiple angles, one of which is consumed regularly, while the other has the insulating ceramic broken and the central electrode shortened, due to manufacturing defects and / or temperature swing

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  Central and lateral electrodes

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  Gap gauge: A disk with a tapered edge; the edge is thicker going counter-clockwise, and a spark plug will be hooked along the edge to check the gap.

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  Spark plug with two side (ground) electrodes

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  Old spark plug removed from a car, new one ready to install.

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  Two spark plug viewers

See also

In Spanish: Bujía para niños