In its basic form, wireless electricity uses the concept of transferring electrical energy from one place to another without the use of wires. Traditionally, all power must be transferred from the source to a device that uses the electricity via some sort of transmission line. However, wireless power uses various forms of transference not requiring this line. Benefits of wireless electricity come in the form of continuous power transmission and the lack of need for wires that can become a nuisance or even hazardous. The transmission of wireless electricity has been used since the late 1800s, but due to commercial restraints, the technological expansion of its use was limited.
The most common form of wireless power transmission is known as near field transference. This uses the concepts of magnetic induction to transfer power over short distances from one location to another. Magnetic induction is commonplace in modern electronics, most notably in the transformer. Two circuits are not connected physically, but used their close proximity to create an electromagnetic field, which transfers power from a source to a device. A primary example of this is the modern electric toothbrush, which fits into a small charging device which, in turn, provides power through metal plates on each part of the device positioned in close proximity to each other.
A different form of wireless electricity can transfer power over long distances. This is known as the far field method and can be used to transfer energy through radio waves, microwaves or lasers. The benefit of this system is its obvious distance advantage over magnetic induction. However, one challenge with the far field method is the fact that the power must be sent in a manner identical to the shape of the receiver. For example, an antenna receiving power via radio waves must be matched to the correct frequency of the source transmission.
After the invention of a way to transfer very high frequency and ultra high frequency radio waves by Heinrich Hertz in 1888, the inventor Nikola Tesla began to develop a way to transfer wireless electricity. By 1891, he was able to patent a method to illuminate light bulbs. This was most notable in his demonstrations at the World's Columbian Exposition in Chicago. While he continued the process, it wasn't until the mid-20th century and beyond that the technique of magnetic induction and wireless power was used commercially. One major challenge lay in the method of charging people for the consumption of power, when it was essentially broadcast to the masses.