Text 18541, 77 rader
Skriven 2007-06-08 01:25:34 av Rich Gauszka (1:379/45)
Ärende: death knell for home electrical outlet?
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From: Rich Gauszka <gauszka@-nospam-hotmail.com>


http://www.dailymail.co.uk/pages/live/articles/technology/technology.html?in_ar
ticle_id=460602&in_page_id=1965

Scientists have sounded the death knell for the plug and power lead.

In a breakthrough that sounds like something out of Star Trek, they have
discovered a way of 'beaming' power across a room into a light bulb, mobile
phone or laptop computer without wires or cables.

In the first successful trial of its kind, the team was able to illuminate a
60-watt light bulb 7ft away.


The team from Massachusetts Institute of Technology, who call their invention
'WiTricity', believe it could change the way we use electricity and do away
with the tangle of cables, plugs and chargers that clutter modern homes.

It could also allow the use of laptops and mobile phones without batteries.

The inspiration came when the lead researcher, Dr Marin Soljacic, was standing
in his kitchen at night staring at his mobile phone.

"It was probably the sixth time that month that I was awakened by my cell phone
beeping to let me know that I had forgotten to charge it. It occurred to me
that it would be so great if the thing took care of its own charging," he said.

To turn this dream into reality, Dr Soljacic needed a way of transmitting power
wirelessly.

Scientists have known for nearly two centuries that it is possible to transfer
an electrical current from one coil of wire to another without them touching.

The phenomenon, called electromagnetic induction, is used in power transformers
and electric motors around the world.

However, the coils in motors and transformers have to be close for power to
pass from one to another. Attempting to transfer power over distances is
impossible.

The breakthrough came when Dr Soljacic realised there was another way of
transferring energy through the air.

Rather than sending power from a transmitter to a receiver as a conventional
electromagnetic wave - the same form of radiation as light, radio waves and
microwaves - he could use the transmitter to fill a room with a 'non-radiative'
electromagnetic field.

Most objects in the room - such as people, desks and carpets - would be
unaffected by the electromagnetic field. But any objects designed to resonate
with the electromagnetic field would absorb the energy.

It sounds complicated, but the result demonstrated by the American team this
month was a dramatic success. Using two coils of copper, the team transmitted
power 7ft through the air to a light bulb, which lit up instantly.

The scientists say the technique works only over distances of up to 9ft.
However, they believe it could be used to charge up a battery within a few
yards of the power source connected to a receiving coil.

Placing one source in each room could provide enough power for an entire house.

The receiver and transmitter would not have to be in view of each other.

Professor Peter Fisher, another of the researchers, said: "As long as the
laptop is in a room equipped with a source of wireless power, it would charge
automatically without having to be plugged in. In fact, it would not even need
a battery to operate inside such a room."

The researchers believe there is little to worry about on safety grounds,
saying that magnetic fields interact weakly with living organisms and are
unlikely to have any serious side effects.

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