|MadSci Network: Engineering|
It certainly is possible to transmit power over the air; obviously the first one commonly used is plain old light, as in solar cells. The same idea can apply to almost any other energy dense electromagnetic radiation, like microwaves. Alternately in close proximity (up to 5 feet) straight induction of a changing magnetic field (where the first order field effects are transferred) is commonly used to power/charge devices. In these scenarios, you aren't practically sending 12V or any other specific voltage, rather you are transferring energy, which can then be converted to whatever voltage you may need. These are probably the most common/practical methods of xferring power over the air. I cannot give you a ready source for information, but this is so common that a simple Internet search using terms: "power" "distribution" "remote" "telepower" "energy" "plugless", should give you a start. --------------------------------------------------------- Madministrator Note: A main issue with providing power wirelessly is that RF and Microwave power transmission tends to be reduced with distance, following the famous "inverse square law". For example, a 40 Watt transmission from a Cellular Transmission station will be generally be reduced to the microwatt range when it reaches a cellular phone a mile away or so. Unfortunately, a few microwatts don't do much in terms of providing power to a device. Power through a transmission line - through power lines and such - tend to drop off more linearly with distance rather than following an inverse square law, because the power does not spread over a spherical area but moves linearly down the power line. Laser light similarly does not spread as severely because it is has so much directionality, being focused in a very thin beam. - Eric Maass
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