Study And Design Of Experimental Apparatus For Interaction Between Permanent Magnet And Moving Non-magnetic Conductor

The interaction between permanent magnet and moving non-magnetic conductor is a kind of electromagnetic induction applied broadly, through theoretical analysis, the moment model about permanent magnet experiences forces is proposed, and permanent magnet can be driven to rotate around the central axis of itself by moving non-magnetic conductor, the phenomenon well reflects the essence of the interaction.We have developed a new kind of experimental apparatus in the paper which combines electronic, electromagnetic, mechanical, computer science, mechanical and automatic control technology etc. The apparatus can be widely used in electromagnetic induction theory teaching and experimental research, it includes hardware circuit design and software design, with microcontroller ADuc832is used. The hardware part consists of magnet is driven by moving non-magnetic conductor measurement circuit, position detection circuit, electromagnet driven circuit, communication circuit, LCD display circuit and photoelectric gate, etc. Software part is composed of modular design, using this device for the research about the interaction between permanent magnet and moving non-magnetic conductor, we got results which are exactly consistent with the theories:when the aluminum cylinder rotates in counter-clockwise direction, the torque received by magnet is always upward; and in clockwise rotation, the speed of aluminum cylinder gradually increased from zero in the process, there is a critical velocity and the torque received by magnet show up after the first down; Using a magnet which is fixed by a U-shaped stand, we found that the moving non-magnetic conductor can drive the magnet rotating.By the experiment result, the rotational speed of magnet approximation is proportional to the velocity of the moving non-magnetic conductor, a tiny fluctuation will appear. In order to solve this problem, using the PASCO company’s magnetic levitation experiment data acquisition system, we can measure relation between the angular acceleration of the permanent magnet and linear velocity of the aluminum plate.Start from molecular current viewpoint, an analytic expression describing the magnetic field distribution in space is derived from the Biot-Savart’s law and principle of electromagnetic field superposition. And the angular acceleration and electromagnetic driving moment is calculated quantitatively when the permanent magnet rotates to any position. The reasons of angular speed appearing periodic tiny fluctuation and the angular acceleration vibrated between positive and negative maximum are due to the joint actions of driving moment and air damping, and this conclusion is consistent with the experimental results.