FAA Powerplant Written Practice Test

Where is the greatest density of flux lines found in a rotating magnet-type magneto?

1. At the edges of the coil

2. When the magnet is in full alignment with the field shoe faces

3. Only when the magnet is disengaged

4. At the point of maximum rotation speed

The correct answer is: When the magnet is in full alignment with the field shoe faces

The greatest density of flux lines in a rotating magnet-type magneto occurs when the magnet is in full alignment with the field shoe faces. This alignment maximizes the interaction between the magnetic field generated by the rotating magnet and the field shoe, resulting in an increased concentration of magnetic flux lines. In this position, the effective area through which the magnetic field lines can pass is maximized, enhancing electromagnetic induction within the coil. As the magnet rotates, when it is aligned optimally, it generates the highest potential voltage and current in the coil, which is vital for the ignition system to function effectively. Understanding this concept is crucial as it illustrates how the design and positioning of the magnet and field assembly directly impact the magneto's performance, especially in terms of voltage generation needed for reliable engine operation.