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MIT Team Powers Light Bulb Without Wires

The MIT system is about 40 percent to 45 percent efficient _ meaning that most of the energy from the charging device doesn't make it to the light bulb. Soljacic believes it needs to become twice as efficient to be on par with the old-fashioned way portable gadgets get their batteries charged.

Also, the copper coils that relay the power are almost 2 feet wide for now _ too big to be feasible for, say, laptops. And the 7-foot range of this wireless handoff could be increased _ presumably so that one charging device could automatically power all the gadgets in a room.

Soljacic believes all those improvements are within reach. The next step is to fire up more than just light bulbs, perhaps a Roomba robotic vacuum or a laptop.

The MIT team stresses that the "magnetic coupling" process involved in WiTricity is safe on humans and other living things. And in the initial experiments on the light bulb, nothing bad happened to the cell phones, electronic equipment and credit cards in the room _ though more research on that is needed.

The harmlessness apparently extends both ways: The researchers noted that putting people and other things between the coils _ even when they block the line of sight _ generally has no effect on the power transfer.


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