Barkhausen effect in different magnetic materials of different size why sound
The purpose of the experiment and the related experimental folding principle [Objective] by the Barkhausen effect of Barkhausen effect to verify the domain theory [] the experiment principle of ferromagnetic materials in the field of magnetization is essentially the domain are gradually changing, and the field domain to expand the domain of different to reduce gradually.
The permalloy film (is the moment not fat loop of ferromagnetic material) into a coil, the permanent magnet N pole to coil and along the coil axis, youyuanerjin permalloy films will be magnetized, the rustle of the horn. If the permanent magnet moves very slowly, the speaker makes a noise. When the permanent magnet does not move, the noise stops immediately and continues to move forward. The horn makes a noise again, and the nearer it gets, the louder it becomes. When the permanent magnet leaves the coil slowly, the horn also makes a noise, but smaller than the magnetization (this is because there is a reversible process in the irreversible process. If it is a good rectangular hysteresis loop material, there is no such phenomenon. The farther the permanent magnet goes, the smaller the sound, until there is no noise. The direction of the magnetic poles unchanged, then moved closer to the permanent magnet coil, permalloy film was again
In the magnetization curve of the steepest area, the mobile domain will appear jump, especially hard magnetic material is even more so. In this experiment, the magnetic jump caused by the change of domain wall is displayed by sound. The operation and experiment phenomenon folded open the instrument back, 4 1 dry cell batteries into the case, the power switch is on, you can begin to do the experiment. 1., the coil does not insert any sample, the permanent magnet along the axis of the coil, from far and near, slowly close to the coil, when the horn no sound. The 2. piece of permalloy (moment is not fat loop of ferromagnetic material) into a coil, the permanent magnet N pole to coil and along the coil axis, youyuanerjin permalloy films will be magnetized, the rustle of the horn. If the permanent magnet moves very slowly, the speaker makes a noise.
