This instrument is a specialized demonstration device for the "effect of magnetic field on current" in physics classrooms and science popularization venues in middle schools and universities. It can visually present the magnitude and direction of Ampere force, helping students quickly establish the spatial concept of "left-hand rule". An electrified conductor oscillates under force in a permanent magnetic field, and the amplitude of the oscillation is proportional to the magnitude of the current. Change the direction of current or magnetic field, observe the change in swing direction, and verify the left-hand rule. Typical experiment: Demonstration of left-hand rule (direction). F=BIL semi quantitative validation (length/current variables). Analogous extension to the principle of "dynamic loudspeaker".