For the wireless charging function, we propose the induction electromotive force to explain in detail about this function.
1， What is Induction Electromotive force？
Induced electromotive force is in the phenomenon of electromagnetic induction since there is an induced current in a closed circuit, there must also be an electric potential in this circuit, the electric potential generated in the phenomenon of electromagnetic induction is called induced electric force.
2， The concept of Induction Electromotive force.
If there is a current in a closed circuit, there must be a power supply in the course, because the current is caused by the electric potential of the power supply. In electromagnetic induction, since there is an induced current in a closed circuit, there must also be an electric potential in the course, and the electric potential generated in electromagnetic induction is called the induced electric potential. The part of the conductor that generates the induced electromotive force is the power source.
3， The history of Induction Electromotive force.
Between 1825 and 1826, Georg Ohm conducted many experiments on electrical circuits, and in 1827, in his book “Die galvanische Kette, mathematisch bearbeitet” (The Mathematical Study of Direct Current Circuits), he discussed many of these experiments and the results obtained from them, including The famous “Ohm’s Law”. Ohm noticed that the power needed for an electric circuit is supplied by a battery, which should be closely related to the various physical phenomena within the circuit. He deduced that the battery had some kind of “driving force” that could drive the current flow in the circuit. He connected several voltaic cells in series and found that the current was proportional to the number of voltaic cells. Therefore, he proposed that the driving force is proportional to the current. This driving force is what we know as the electric potential, which in a simple resistive circuit is equal to the current times the resistance.
Later, in 1831, Michael Faraday did a series of experiments on electromagnetic induction, from which he found the following.
When changing the current in the current-carrying wire, a current is induced in the nearby closed circuit.
When moving the magnet, the nearby closed circuit will be induced current.
When moving a closed circuit near a current-carrying wire or magnet, a current is induced in this closed circuit.
In 1832, Faraday also discovered that the induced currents in different wires are proportional to the conductivity of the wire. Since the conductivity is inversely proportional to the resistance, this shows that induction involves an electric potential and that the induced current is formed by the electric potential driving the charge of the wire; moreover, the electric potential is induced regardless of whether the wire is an open or closed circuit.
4， The Description of Induction Electromotive force.
- Regardless of whether the circuit is closed, as long as the magnetic flux through the circuit changes, the circuit will produce an induced electric potential, the generation of induced electric potential is the essence of the electromagnetic induction phenomenon.
- Whether the magnetic flux changes are the fundamental cause of electromagnetic induction. If the magnetic flux changes, the circuit will produce the induced electric potential, and then if the circuit is closed, the circuit will have induced current.
- The generation of the induced current is only a phenomenon, it means that the circuit is conveying electrical energy, and the generation of induced electric potential is the essence of the electromagnetic induction phenomenon, which means that the circuit has the ability to output electrical energy at any time.
- In the flux change △φ the same, the greater the time △t, that is, the slower the flux change, the smaller the induction potential E; conversely, the smaller △t, that is, the faster the flux change, the greater the induction potential E.
- When the change time △t is the same, the larger the change △φ, the faster the flux change, and the larger the induced electric potential E. Conversely, the smaller the change △φ, the slower the flux change, and the smaller the induced electric potential E.
