FAA Powerplant Written Practice Test

What are the distinct circuits found on a high-tension magneto?

1. Magnetic and Alternating current circuits

2. Primary and Secondary circuits

3. Magnetic, Primary, and Secondary circuits

4. Fuel and Ignition circuits

The correct answer is: Magnetic, Primary, and Secondary circuits

In a high-tension magneto, the distinct circuits include both the primary and secondary circuits, as well as the magnetic circuit. The primary circuit is responsible for the initial input of energy into the magneto. It contains components such as a coil wound with a few turns of wire, a magnet, and points that open and close the circuit. This circuit generates a low-voltage current when the magnet rotates, which leads to the collapse of the magnetic field. The secondary circuit is designed to step up the voltage generated by the primary circuit to a much higher voltage, which is necessary for igniting the fuel-air mixture in the engine's combustion chamber. This circuit consists of a coil with many turns of wire, where the high voltage is induced during the collapse of the magnetic field from the primary circuit. Additionally, the magnetic circuit is present as it involves the magnet and its magnetic field, which are crucial components for the operation of the magneto. The interaction of the magnet with the coils is what ultimately generates the electrical current necessary for ignition. In summary, the correct answer encompasses all three circuits—magnetic, primary, and secondary—since they work together to enable the magneto to function effectively for engine ignition.