The principle of wireless charging is to use electromagnetic wave induction. The process is similar to the power transformer. There is a coil at the sending and receiving end. The sending end coil connects wired power to generate electromagnetic signal and receives the electromagnetic signal from the end loop to induce the current to charge the battery. The principle of wireless charging technology can be traced back to 1830s. Michael Faraday, the scientist, first discovered the principle of electromagnetic induction, that changes in the surrounding magnetic field will cause electric current in the wire. By 1890s, an assistant to the Edison spectral radiant energy research project and a later scientist, Nicola Tesla, confirmed the possibility of radio transmission.
At present, there are four different commercial technologies in wireless charging: electromagnetic induction technology, radio wave technology, electromagnetic resonance technology and electric field coupling technology. The technology of wireless charging mainly used in mobile phone is electromagnetic induction and electromagnetic resonance technology. Of course, wireless power supply will have broad prospects for future home appliances and electric vehicles with strong momentum of development. Once wireless charging breaks through technical barriers, while ensuring conversion, security and ease of use, efficient and fast charging will be as described in the science fiction "three bodies", bringing further productive forces to human beings. Here, let's just talk about electromagnetic induction and electromagnetic resonance related to cell phone charging.