One of the early pioneers of electricity, Nikola Tesla, built a 29-metre tower at Wardenclyffe-on-Sound on Long Island, New York. The tower project lasted from 1901 to 1917 and was undertaken to show the commercial viability of trans-Atlantic communication. Another function was to show how electricity could be transmitted without the use of connecting cables.
The Wardenclyffe Tower never became fully operational and the venture was shut down when it ran out of money.
Matched Resonance Frequency
Today, WiTricity Corporation of Watertown, Massachusetts has demonstrated what Nikola Tesla was not able to do. At the TED Global conference in Oxford, England in July 2009, the company showed how it is possible to charge televisions and mobile phones without cables.
The principle behind the idea is the same as the transmission of sound waves. Describing the system for BBC News (July 23, 2009), science reporter Jonathan Fildes writes that it “exploits ‘resonance,’ whereby energy transfer is markedly more efficient when a certain frequency is applied.
“When two objects have the same resonant frequency, they exchange energy strongly without having an effect on other, surrounding objects.”
It’s similar to the way in which an opera singer can shatter a glass from the other side of a room by hitting a note that perfectly matches the natural resonance of the container.
Two Coils used in Power Transfer
In describing the technology WiTricity says “A loop or coil of conductive material like copper, carrying an alternating current (AC), is a very efficient structure for generating or capturing a magnetic field.
“If a conductive loop is connected to an AC power source, it will generate an oscillating magnetic field in the vicinity of the loop. A second conducting loop, brought close enough to the first, may ‘capture’ some portion of that oscillating magnetic field, which in turn, generates or induces an electric current in the second coil.
“The current generated in the second coil may be used to power devices.” The process is called magnetic induction.
Many Applications for Wireless Electricity Technology
According to the BBC, the company’s chief executive Eric Giler “showed off a commercially available television using the system.
‘Imagine you get one of these things and you want to hang it on the wall,’ he said. ‘Think about it, you don’t want those ugly cords hanging down.’ ”
The company says residential applications include wireless recharging of mobile electronics equipment, direct wireless powering of home entertainment devices, and powering computer peripherals – mouse, keyboard, printer, speakers, etc. – eliminating the tangle of cables surrounding most PCs.
For the industrial market, the company sees the technology can be used with robots, packaging machinery, and machine tools. It could also be used in drilling and underwater where running cables is impractical.
Giler points out trillions of dollars have been invested building an infrastructure of wires “to get power form where it is created to where it is used.” A lot of that could be eliminated by using wireless transmission.
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