Final answer:
The three distinct circuits in a high-tension magneto are the magnetic circuit, the primary electrical circuit, and the secondary electrical circuit.
Step-by-step explanation:
The three distinct circuits of a high-tension magneto are the magnetic circuit, the primary electrical circuit, and the secondary electrical circuit. The magnetic circuit comprises the magnets and the soft iron core that concentrates the magnetic field. The primary electrical circuit includes the primary coil windings, points, condenser, and the switch controlling these components. Finally, the secondary electrical circuit consists of the secondary windings of the coil, which step up the voltage generated in the primary to a high tension suitable for spark plug ignition. High-tension magnetos are crucial for generating a high voltage spark in internal combustion engines, using principles such as Faraday's Law of Induction and Lenz's Law for converting mechanical energy into an electrical spark.