Wireless Power: Charging Over the Air

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As I absently kick the many power cords under my desk, it's hard not to love the idea of wireless power. We've managed to uncouple our devices in many other ways, but when it comes to charging up our batteries, we have to plug in a cable or otherwise make contact with a power source.

Maybe not for much longer. Researchers at MIT have successfully implemented what had previously been a theoretical system for delivering power via electromagnetic waves; in their tests, they lit a 60-watt lightbulb that was sitting seven feet away from its power source.

The system exploits pretty basic physics. A transmitting copper coil was attached to the power source, and a similar coil to the light bulb. The two coils resonated at 10 MHz, which led to gathered energy flowing between them -- even when solid objects were placed between them.

(The question you might then ask is, what if the solid object between them is a person? Will they burst into flame, grow extra arms, or suddenly become super-geniuses? Sadly, no. Unlike microwaves, which have very small wavelengths, the longer waves of a 10 MHz field have a minimal effect on people.)

Researcher Marin Soljacic describes the system as "rudimentary," which is apt as both coils are a good two feet in diameter. Their challenge now is to create a more compact system, that transmits power with greater efficiency (they're currently at about 40 percent efficiency), possibly over greater distances. But so far as I'm concerned, the beauty of the system is that it isn't based on much more than college-level physics. It's kind of nice to see simple, elegant solutions once in a while.

This story, "Wireless Power: Charging Over the Air" was originally published by PCWorld.

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