Cars+Group+3

=__**Group 3**__ __**Spark Plugs**__=

__Spark Plug__
A **spark plug** (in [|British English], a **sparking plug**) is an electrical device that fits into the [|cylinder head] of some [|internal combustion engines] and ignites compressed [|aerosol] [|gasoline] by means of an electric spark. Spark plugs have an insulated wire which is connected with a [|induction coil] or [|magneto] circuit on the outside, and forms, with another terminal on the base of the plug, a [|spark gap] inside the cylinder. The spark plug was invented by [|Nikola Tesla], Spark plugs may also be used in other applications such as [|furnaces] where a combustible mixture should be ignited. In this case, they are sometimes referred to as **flame igniters**. Spark plugs are typically designed to have a variable spark gap. The spark gap may be adjusted by the technician installing the spark plug. A //spark plug gap [|gauge]// or [|feeler gauge] is used to set the gap. The simplest gauges are a collection of keys of various thicknesses which match the desired gaps and the gap is adjusted until the key fits snugly. Internal combustion engines can be divided into //spark-ignition engines//, which require spark plugs to begin combustion, and //compression-ignition engines// ([|diesel engines]), which compress the fuel/air mixture until it spontaneously ignites. Compression-ignition engines may use [|glow plugs] to improve cold start characteristics.

__**Operations**__ The spark plug is connected to the high voltage generated by the coil. As the electrons are pushed in from the coil, a voltage difference appears between the center electrode and side electrode. No current can flow because the fuel and air in the gap is an insulator, but as the voltage rises further, it begins to change the structure of the gases between the electrodes. Once the voltage exceeds the [|dielectric strength] of the gases, the gases become [|ionized]. An ionized gas becomes a conductor and an ionized gas can pass electrons. As the current of electrons surges across the gap, it raises the temperature of the spark channel to 60,000 [|K]. The intense heat in the spark channel causes the ionized gas to expand very quickly, like a small explosion. This is the "click" you hear when watching a spark. The heat and pressure force the gasses to react with each other and at the end of the spark event there should be a small ball of fire in the [|spark gap] as the gases burn on their own. The size of this fireball or kernel depends on the exact composition of the mixture between the electrodes and the level of combustion chamber turbulence at the time of the spark. A small kernel will make the engine run as though the ignition timing was retarded and a large one like the timing was advanced for that individual cycle.

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Alexis and Nick - Show how they work by taking a spark plug and making it spark Amanda and Emily- Explain how you could start your car without one Kayla K & Sienna g- Explain what makes your spark plugs so bad. Kayla & Hanna: Where is the spark plug located? Norbert and Ethan - How long does it take for one to wear out? Julie, Cindy, Sarah - Explain the relationship between the spark plugs and the battery! Paul and Dylan- Factors that cause spark plugs to not work anymore Amanda and Katelynn - explain how they get the right amount of air and gasoline for the spark plug.