WiTricity-Know The Wireless Electricity

Perhaps you know what WiFi is?? Keeping the same thing in mind, wireless electricity has been named WiTricity by Team of Research scientist in MIT who demonstrated wireless electricity by lighting a 60W light bulb kept 2 meters away from the source of electricity. How did they do it?? Let’s find out.

It was Nikola Tesla in late 1800 who first proposed wireless electricity but he was not entirely successful. Later some other scientist tried to modify Tesla’s experimentation of Wireless electricity but in vain. What they did was based on how transformers work today i.e. mutual induction. They worked on two coils, one primary and the other secondary. Current in the first coil induces a magnetic field, this magnetic field couples with the secondary coil to give an output current. But this has many disadvantages. First, the coil needs  to be kept very close to each other, if the secondary coil is taken far from the output then current lags in magnitude to a huge extent compared to primary. To compensate the current loss the intensity of magnetic field can be made stronger at primary by introducing more round of coils but this would waste a huge amount of magnetic field and hence energy since only a part of primary coil’s magnetic field will be coupled. Thus mere mutual induction can’t be used to transmit electricity due to huge inefficiency.

The WiTricity Team and at right an mutual inductive charger

WiTricity uses the similar concept like above but with added resonance to it. The primary coil is made to vibrate at a particular frequency (its resonance frequency); if this frequency matches with the secondary coil’s frequency then transfer of electricity with power loss can be obtained. Thus both the coil must have that much of current with the same resonate frequency. Added resonance changes the construction of the coil to some extent as well. The coil is throughout inductive with capacitive plates at its ends to store the charges, this is how the WiTricity team lit a 60W bulb wirelessly.

WiTricity Demonstartion,

Future Home using Electricity, Source: HowStuffWorks

David Criswell of the University of Houston proposed use of microwave to transfer electricity. He also tells that Solar cell station can be constructed at the Moon from where electricity will be directed to earth via microwave band of spectrum but again the question of maintenance of the solar cell at Moon is questionable. Furthermore microwave may also have health hazards.

NASA also proposed the use of infrared to transfer electricity to charge batteries and they have even used it but infrared requires direct line of sight with object for the transfer thus making it less feasible for the future.

Iamge Source: treehugger.com

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Refer http://www.witricity.com/index.html