The technology behind wireless charging has been around for over a century. Nikola Tesla first demonstrated the transmission of energy with his famous Tesla Coil which most people recognize as a shiny sphere that emits sparks of electricity.
Tesla invented the coil in 1892; its technology is used extensively in radios, televisions, and countless other devices. Wireless charging utilizes wire coils in both the transmitting and receiving devices to transfer power using electromagnetic induction.
Current in the transmitting device, the charger, excites electrons in the receiving device, a smartphone or other similar device, that is used to charge the batteries. The coils are designed specifically to match the application while considering various parameters such as charging voltage, charging current, distance between the devices and much more.