Abstract: A first magnet is mounted for rotation near a cavity of a magnetizable body such that the first magnet has a null position influenced by magnetic interaction between said first magnet and at least two pole pieces of the magnetizable body. The magnetizable body has a core associated with a source of magnetic energy to induce magnetism within the core and the pole pieces and thereby alter the null position of the first magnet. Various embodiments of the invention include: analog meter mechanisms; actuators; transducers; proximity and position indicators; and other devices.