Take the external magnetic control wheel as an example. The external magnetic control wheel consists of cast iron flywheel, conductive layer (aluminum plate or copper plate) coated on the edge of flywheel and magnet assembly. Cast iron flywheel provides inertia and acts as a magnetic conductor, forming a magnetic field as shown in the figure.
The magnets in the magnet assembly are composed of permanent magnets, and their magnetic poles are distributed as shown in the figure. The aluminum plate or copper plate of the conductive layer will cut the magnetic field through the rotation of the flywheel, which will produce magnetron resistance to the iron assembly.
Therefore, the magnitude of magnetoresistance, that is, the magnitude of Lorentz force F.
f = q×v×B；
Q is the charge of charged particles, which is equivalent to current. At the same voltage, the smaller the resistance of the conductive layer, the greater the current and the greater the resistance. This is why the resistance of copper sheet is greater than that of aluminum sheet.
V is the speed of charged particles, that is, the speed of flywheel. The faster the speed, the greater the resistance.
B is the magnetic induction strength, which is related to the surface magnetic field strength and magnetic gap of the permanent magnet. The greater the magnetization of the magnet, the greater the magnetoresistance; The smaller the magnetic gap, the greater the magnetic field strength and the greater the resistance, and vice versa. In fact, the magnetic wheel adjusts the resistance by adjusting the magnetic gap.
Information is collected from the Internet.