Tunneling magnetoresistance method Therefore, when the short circuit line electromotor external played a electromagnetic damping effect on rotor. Resting after shaking, can observe the pointer to swing repeatedly, after a certain time to rest down. If the circuit is closed coil in the coil, will produce induced current. Manipulation Equipment agile galvanometer, wire etc.. And manipulation (2) form a significant contrast. In the process of preventing the move or transport, galvanometer by the vibration amplitude, the pointer is too large and bumped to bend the shaft tip off or etc.. Rotor coil with induction current, by the braking action of Ampere force moment of couple, will make rapid endless rolling down. This is because the coil is connected with a pointer swing when the magnetic field induction current is generated, the moment of resistance coil is formed by the action of Ampere force, so that the pointer swing rapidly decay. (1) usually JD409 or JD409-1 type quick damping time meter is less than 4S, due to the moving coil galvanometer the agile aluminum box is closed, the damping effect has a certain. Immediately on the two terminal is connected to a wire (shortest path), can be found in the pointer swing decreases rapidly, not even the shortest route than the swing time much shorter. (2) the single pole double position switch to a, electromotor is high speed rolling. (3) once again shake agile galvanometer, which have larger swing. So this demo is best to adopt agile galvanometer old-fashioned (is not a closed internal coil aluminum frame), better damping effect demonstration short circuit. Explain (1) rocking the agile galvanometer has even on short routes, visible pointer swing amplitude is very small, and fast stop. The reason the same manipulation (2). Manipulation Equipment toy motor, single pole, double switch, batteries, wires etc.. This is because the electromotor rotor has a high rolling, in cut off power supply, is still in the magnetic field in the rotor of high speed rolling, will produce the induced electromotive force. This can play the role of damping conservation. (1) the toy electric motors, two batteries, single pole double switch connected with the wire as shown in figure. If then the external circuit closed (such as switch to b), in a circuit that generates induction current, then the equivalent of a generator. (3) again will switch to the a electric motor, high speed rolling, is a single pole double position switch to B. Objective to demonstrate the short-circuit protection agile galvanometer. Found that the electromotor will quickly endless rolling. Note from the dump to a complete halt time. The magnetic field on the induced current will generate ampere force, formation and the original rolling in the opposite direction to the moment of couple, coil rolling damping effect. Short circuit braking method objective demonstration of electromotor. Method Coil rolling in magnetic field, can generate the induced electromotive force. (1) the agile galvanometer after shaking, so that the pointer swing larger. The following two methods, respectively, demonstrating shortest route after connected, the electromagnetic damping effect on agile galvanometer and motor. Cut off the power supply, the visible electromotor power, still can be maintained for a longer time, rolling. Method two (2) the experiments that agile galvanometer when not in use, should be added to the short line in the two terminal, in order to achieve the effect of damping conservation. Dongguan Jincheng Industrial Co., Ltd. is a research and development, manufacturing, sale of tension control, magnetic damper, as one of the professional manufacturers, the main production: tension device series, magnetic damper series, tension device, magnetic damper, magnetic damper damper, damper, and other goods. Www.www.swlawyer.org.cn