WiTricity: Power can be sent through thin air

Discussion in 'General Science & Technology' started by common_sense_seeker, Feb 26, 2010.

  1. common_sense_seeker Bicho Voador & Bicho Sugador Valued Senior Member

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  3. cosmictraveler Be kind to yourself always. Valued Senior Member

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    Oh wow, it traveled 7 inches and lit a bulb! How much energy was needed to do this? Then how much was lost seeing as how the transmission would be going in all directions when transmitted.
     
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  5. Read-Only Valued Senior Member

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    Wow - you sure go nuts easily! Of course it's not related to the Norwegian event - that was a Russian rocket failure than caused the rocket to spin as fuel blew out sideways.

    Basically, the WiTricity device just employs induction but with a highly boosted effect due to tuning for magnetic resonance. The latter making it MUCH more efficient than plain induction alone. It's actually pretty simple, basic electrical principles at work.
     
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  7. TBodillia Registered Senior Member

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    And Faraday did the same thing how long ago?
     
  8. Pinwheel Banned Banned

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    Lots of comments about Nicolas Tesla doing this up to 20 miles away. When?
     
  9. TBodillia Registered Senior Member

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    Tesla! Why did I write Faraday? So stoopid at times!!!
     
  10. ElectricFetus Sanity going, going, gone Valued Senior Member

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    Electrical transmission over range through air is usually very inefficient, there are several known mechanisms to achieve this, the most popular (and efficient) is induction: Using AC current wrap around a magnet (or no magnet is some designs) can induce current up to many cm away or more depending on input current coil size and acceptable losses, certainly much less than a meter is feasible without having to resort to superconducting magnets or coils of impractical sizes. Another is microwaves: microwave transmitters and receives have achieve a combine efficiencies as high as 85% in transmitting electricity, this makes them less efficient then wires (>93% over nation wide grids) but has been used in a few cases for power transmission, it is the best option for getting power from orbital solar power plants, require a gigantic transmitters (and gigantic orbital solar arrays) and even bigger (though immobile and very simplistic) receiver across several km of the earth surface.

    Tesla was obsessed with electrostatics induction, which never managed any proven transmission distances greater then normal electromagnetic induction and for power transmission would be less efficient and far more dangerous.

    http://en.wikipedia.org/wiki/Wireless_energy_transfer
     
  11. common_sense_seeker Bicho Voador & Bicho Sugador Valued Senior Member

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    Thanks for all your useful comments.
     
  12. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    I liked it better when it was called radio.
     
  13. Read-Only Valued Senior Member

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    Heh-heh-heh! Point taken, Mac, but it sure isn't quite the same thing.

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    Radio doesn't employ tuned magnetic resonance coupling - which is what makes this stuff efficient. In a radio transmission, considerably over 99.99% of the energy is wasted and never recovered.
     
  14. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    Your right...I was just trying to make a funny.

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    CSS, whenever you move a magnetic field over a conductor (or vise versa) it induces or "creates" (not really a correct term) a voltage in that conductor. Alternately, if you run electricity through a conductor, it creates a magnetic field around the conductor. If you coil up that conductor, it creates a larger surface area in a smaller space, so more of the EM field gets converted to electricity, or electricity to EMF. It's how transformers work.

    That's just the "technicians" explanation...I'm sure we have a few engineers that could explain it more correctly.
     
  15. Read-Only Valued Senior Member

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    Yep, I gotcha - that was why I started off my response with a little laugh.

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    Nice, Mac, you got it off to a good start.

    I could write a whole book here - but rather than that, I'll add just a bit about the "coupling effect."

    In a simple transformer, a lot of energy can be wasted. But that can be improved *considerably* by tighter coupling. And that's achieved by simply placing the primary and secondary windings in closer proximity and by adding a magnetic core such as soft, easily magnetized iron. The latter keeps the magnetic field more closely confined, thus adding to to the energy transfer that would be wasted if it were allowed to simply expand into space beyond the windings.

    And here's a very common example of tuned coupling energy transfer: Your radio or TV has a tunable receiver. If you tune the TV to, say channel 6, the energy being broadcast on channel 6 will be picked up and used by your TV to display the content. But at the same time, the energy being broadcast on ALL the other channels does nothing for you - it's completely wasted *because* your tuned circuit cannot receive it (and actually REJECTS it). And the same principle applies to the tuned magnetic coupling of the WiTricity transmitter and receivers. The closer they are tuned *together*, the more efficient the energy transfer is.
     

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