FAA Powerplant Written Practice Test

What is the radial location of the two North poles in a four-pole magnet of a high-tension magneto?

1. 90 degrees apart

2. 180 degrees apart

3. 270 degrees apart

4. 360 degrees apart

The correct answer is: 180 degrees apart

In a four-pole magnet of a high-tension magneto, the two North poles are indeed located 180 degrees apart. This configuration is essential for the proper functioning of the magneto. A four-pole magnet consists of two North poles and two South poles arranged in such a way that they are symmetrically spaced around the axis of the magnet. When the North poles are situated 180 degrees apart, it allows for a balanced magnetic field, ensuring that the rotating armature or rotor can effectively induce the desired voltage in the coil. This setup contributes to the efficient generation of electrical energy necessary for the ignition system of an aircraft engine. The other options do not correspond to the arrangement of the poles in a four-pole magnet. Since the poles need to be symmetrically placed to establish a proper magnetic field for functioning, any other arrangement, such as 90 degrees or 270 degrees apart, would lead to an imbalance and ineffective magneto operation. A full 360 degrees would imply that the poles overlap, which is not practical for the intended operation. Thus, having the North poles positioned 180 degrees apart is crucial in the design of a four-pole magnet.