Final answer:
A magneto ignition system produces a spark when the breaker points begin to open, using a rapidly spinning magnet to induce a high voltage across the coil which can jump the gap in the spark plug.
Step-by-step explanation:
How does a Magneto Ignition System Produce a Spark?
The spark in a magneto ignition system is created when the breaker points are just beginning to open. A magneto is essentially a small generator that works by spinning a magnet at high speeds near a wire coil. The changing magnetic field as the magnet spins induces an electrical current in the coil through the phenomenon known as electromagnetic induction. When the breaker points start to open, the circuit is interrupted, causing a rapid reduction in current which, in turn, induces a high voltage in the coil. This sudden high voltage is sufficient to jump across the small gap in the spark plug, creating a spark.
The magneto's basic principle leverages Faraday's Law of Electromagnetic Induction, which states that a changing magnetic field in a circuit induces an electromotive force (EMF) in that circuit. The faster the change in the magnetic field, the larger the induced EMF will be. That's why the magnet in a magneto needs to spin quickly—to maximize the rate of change in the magnetic field and to generate the large voltage necessary for creating the spark.
Furthermore, when the magnitude of an external electrical field becomes too large, the molecules of the dielectric material between the breaker points can start to ionize, aiding in the creation of the spark. This process is critical for the operation of engines in various types of machinery, especially in aviation and other applications where reliable engine ignition systems are crucial.