The Law of Electromagnetic Induction and Its Applications

  Overview:

The law of electromagnetic induction is also called Faraday's law of electromagnetic induction. The phenomenon of electromagnetic induction refers to the phenomenon of induced electromotive force due to the change of magnetic flux. For example, when a part of the conductor of a closed circuit moves to cut the magnetic field line in the magnetic field, a current will be generated in the conductor. The resulting current is called induced current, and the resulting electromotive force (voltage) is called induced electromotive force.

The direction of the electromotive force in the law of electromagnetic induction can be determined by Lenz's law or the right-hand rule. The content of the right-hand rule: Extend the right hand so that the thumb is perpendicular to the four fingers, the palm is facing the N pole of the magnetic field, the direction of the thumb is consistent with the direction of the conductor movement, and the direction pointed by the four fingers is the direction of the induced current in the conductor (the direction of the induced electromotive force). same direction as the induced current). Lenz's law states that the magnetic field of the induced current should hinder the change of the original magnetic flux. In short, as the magnetic flux increases, the generated current tends to decrease; while the magnetic flux decreases, the generated current tends to increase.

The magnitude of the induced electromotive force is determined by Faraday's law of electromagnetic induction; e(t) = -n(dΦ)/(dt). E=BLV can also be used to find the case of motion.

Application:

Dynamo

The electromotive force caused by the relative motion of the circuit and the magnetic field by Faraday's law of electromagnetic induction is the fundamental phenomenon behind the generator. When a permanent magnet moves relative to an electrical conductor (and vice versa), an electromotive force is created. If the wire is now connected to an electrical load, current will flow, thereby generating electrical energy, converting the energy of mechanical motion into electrical energy. For example, drum generators. Another generator that implements this idea is the Faraday disc.

Transformer

The electromotive force predicted by Faraday's law is also the operating principle of the transformer. When the current in the coil transitions, the transitioning current generates a transitioning magnetic field. The second wire in the range of the magnetic field will feel the change in the magnetic field, so its coupled magnetic flux will also change. Therefore, there will be an electromotive force in the second coil, which is called the induced electromotive force or transformer electromotive force. If both ends of the coil are connected to an electrical load, current will flow.

Electromagnetic Flowmeter

Faraday's law can be used to measure the flow of conductive liquids or plasma-like objects, such an instrument is called an electromagnetic flowmeter.