Transformer: How Voltage is Amplified or Attenuated
A transformer is used to convert an input voltage \( U_1 \) into an output voltage \( U_2 \) by utilizing electromagnetic induction.
The ignition system of a gasoline engine operates by exploiting the law of electromagnetic induction. For this purpose, a transformer is used, consisting of two closed circuits. In the primary circuit, a voltage \(U_1\) is applied to the primary coil, which has \(N_1\) windings. In the car, the \(12 \, \mathrm{V}\) battery provides this voltage. The circuit can also be interrupted by turning the car key.
In the secondary circuit, the secondary coil with \(N_2\) windings and a spark plug are connected. When the voltage \(U_1\) is interrupted by turning the car key, according to the law of electromagnetic induction, a voltage \(U_2\) is induced in the secondary circuit. In order to generate an electrical spark at the spark plug, the contacts (electrodes) of the spark plug must be as close as possible, and a high voltage must be induced. A high voltage in the secondary circuit can be generated by choosing a larger number of windings \(N_2\) for the secondary coil, in contrast to \(N_1\):
The spark from the spark plug ignites the engine.