MIT crafts wireless electricity

How many scientists does it take to turn on a lightbulb?

A team of scientists from MIT has come up with a way to light a 60-watt lightbulb. The trick is that the bulb is located about seven feet from the power source and no wires connect the two.

Wireless electricity, or "WiTricity" as MIT likes to call it, could one day allow consumers to carry notebooks or cell phones without batteries. It could also make it easy for contractors to remodel homes. Someday. To make it happen, the waves would need to be targeted and tracking mechanisms would need to exist to link the power source and the intended target.

Various techniques for transmitting power wirelessly have been around for years. Radio is an example. Transmitting electrical power, however, is tricky.

WiTricity couples resonant objects: the source and recipient resonate on the same frequency, allowing them to communicate efficiently without interfering with other objects. MIT analogizes this to an opera singer and 100 wine glasses. If the wine glasses all contain different amounts of liquid, they will resonate at different frequencies. When the singer hits a particular frequency, one glass will shatter but others will remain unaffected.

In the MIT experiment, the scientists used two copper coils to create the wireless link between the power source and the bulb. The scientists found there was strong interaction between the sender and receiver and only weak interaction between the sender and the ambient environment.

Further details will be spelled out in the June 7 issue of Science Express.

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