Intel Demos Wireless "Resonant" Recharging 184
Al writes "Last Thursday researchers from Intel demonstrated a way to recharge electronics from about meter away using a 'resonant' magnetic field. At an event held at the Computer History Museum in Mountain View, the researchers showed off a pair of iPod speakers connected to a 30-centimeter-wide copper coil that received power from a similar, but larger, copper coil about a meter away. The recharging technique relies on a phenomenon called resonant coupling, in which objects can exchange energy when tuned to resonate at the same frequency. A similar approach was developed by researchers at MIT in 2007, and spun off into a company called WiTricity. This company has already developed a few products that use resonant coupling to recharge, including a car battery."
Troll Explosion (Score:0, Informative)
Why are there so many replies in this topic modded as "Troll"? Even ones that clearly are not trolls. Is someone trolling the mod system?
Nothing new here (Score:4, Informative)
Re:power consumption (Score:3, Informative)
Re:power consumption (Score:3, Informative)
what happens if you place a HDD, or your phone contains a HDD and is charged using this method, wont the magnetic field damage the magnetic media??
Most HDD's are pretty well shielded, nowadays. Remember also that the receiving coil (in this case) is a 707 cm^2 wire coil, while the surface area of the hard drive in the magnetic field is likely no more than a few cm^2. (The energy absorbed by an object in this situation is proportional to its surface area in the plane perpendicular to the electric field, among other things.)
does the power consumption increase or decrease based on the number of receiving coils??
The power consumption in the primary would increase. Given the case of two coupled inductors (the two coils seen here), a mutual inductance couples the two and a "reflected impedance" is seen on each of them due to the effect of the other. In other words, if the receiving coil was consuming large amounts of power, a significant series load would appear on the transmitting coil, causing either a drop in the voltage and the transmitted power (if you hold the power consumed by the transmitting coil constant) or an increase in the consumed power (if you hold the transmitted power constant).
Re:Dumb question... (Score:3, Informative)
Obviously nothing is 100% efficient...
Actually super conductors are. They really have zero resistance. Unfortunately the temperatures involved mean that they are not very practical.
Re:Dumb question... (Score:3, Informative)
um... what?
Did you mean "the RESISTANCE of the cord is nothing compared to the impedance of the transmission mechanism"? Impedance is ideally lossless... the reduction in current comes from capacitance and inductance which only store and redirect current instead of turning it into heat like resistance does.
And your nitpick doesn't make any sense either. Just because one part of a transmission line is super conducting doesn't mean it all is. It's like switching between different resistance cables in your power transfer... what happens in one part of the line doesn't mean anything about the rest of the wire.
The real problem with the efficiency of super conducting cables is the cost that goes into keeping them cool. You have to count that massive expenditure of energy against it when doing efficiency calculations.
In the end, 2gravey is right, copper is one hell of a good conductor (the only material that I know is better is silver, and it's not better by much) so its rarely possible to improve on a good copper wire other than to make it a thicker copper wire.
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