Monday, June 11, 2007


Physicists at MIT have discovered a method of transmitting energy without the use of cables or batteries. They have dubbed the concept "WiTricity," as in Wireless-Electricity.

To showcase the new technology, physicist Marin Soljacic powered a 60-watt bulb from 7 feet away (picture, below).

The difficulty with wireless power transmission is, like radio waves, the energy radiates in all directions. The result is a tremendous amount of wasted energy -- and therefore, minimal efficiency.

What Soljacic and his collegues focused on was the development of a method using resonant electromagnetic waves. The principle is quite simple: two objects resonating at the same frequency tend to exchange energy efficiently, while interacting weakly with objects not resonating at the same frequency.

Since the majority of common objects interact weakly with magnetic waves, very little power is lost on unintended targets.

"The fact that magnetic fields interact so weakly with biological organisms is also important for safety considerations," said Soljacic's colleague, MIT physicist Andre Kurs.

In their latest work, the scientists designed two copper coils roughly 20 inches in diameter that were specially designed to resonate together. One was attached to the power source, the other to a light bulb.

Of course, the applications of this cutting-edge technology are numerous. Laptops, MP3 players and cell phones come immediately to mind; no more batteries, no more hassling with cords.

"As long as the laptop is in a room equipped with a source of such wireless power, it would charge automatically, without having to be plugged in," said MIT researcher Peter Fisher, also part of the research team. "In fact, it would not even need a battery to operate inside of such a room."

The researchers demonstrated roughly 40 percent efficiency in power transfer. Kurs told LiveScience they are currently working on improving the efficiency of the power transfer as well as the maximum distance allowed.

"For the moment, we are focusing on power transfers on the order of 100 watts although, in principle, more power could be transferred," he added.

Exciting to think about, is it not? A home with no outlets, and no extension cords -- simply place your lamps, coffee pot, television, microwave and computers wherever you like.

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