Final answer:
The rotating magnet in a high-tension magneto is positioned to induce the greatest magnetic flux change through the coil just before the piston reaches the top of the compression stroke, at the ignition point.
Step-by-step explanation:
In a high-tension magneto, the approximate position of the rotating magnet when the points first close is at the position where it can induce the largest change in magnetic flux through the coil. This typically occurs just before the piston reaches the top of its compression stroke in an engine, known as the 'ignition point'. The exact position can vary depending on the specific design of the magneto and the engine it is paired with.