FAA Powerplant Written Practice Test

Which of the following represents the circuits of a high tension magneto?

1. Magnetic and primary only

2. Secondary and grounding only

3. Magnetic, primary, and secondary

4. Primary and charging only

The correct answer is: Magnetic, primary, and secondary

The correct representation of the circuits of a high tension magneto includes the magnetic circuit, primary circuit, and secondary circuit. In a high tension magneto, the magnetic circuit is essential for creating the magnetic field needed to induce voltage. The primary circuit is responsible for initially charging a capacitor or other energy storage device with low voltage. When the primary circuit is interrupted (typically by the action of the breaker points), the energy stored is transferred to the secondary circuit, which greatly increases the voltage to levels suitable for spark generation in the spark plug. The secondary circuit operates at high voltage, which is necessary to ensure that the electrical discharge can jump the spark plug gap, igniting the fuel-air mixture in the engine's combustion chamber. Understanding the interaction between these circuits is crucial, as the failure of any one of them can disrupt the operation of the magneto, leading to inadequate engine performance or failure to start. Thus, the comprehensive involvement of the magnetic, primary, and secondary circuits accurately represents the function and operation of a high tension magneto.