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Can you send 60hz waves through the air to charge iPods? Answered

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NobodyInParticularBest Answer (author)2009-04-08

Yes, you can transmit power wirelessly, but at the cost of either interference, short distance, or giant antennas and low efficiency. (In any case, 60 Hz is not such a good idea: without some fancy engineering tricks, a 60Hz antenna would involve a wire that was some significant fraction of 3100 miles long.)

A crystal radio reciever is an early type of radio that is powered entriely by the radio station. It consists of just earphones, an antenna, a tuner, and a diode.

Transmitting power across less than an inch is quite practical. I suspect that in the next few years, Apple designers will come up with a model of iPod that charges and transmits signals wirelessly, so they will no longer have to destroy the perfect smoothness of the case with a power/data jack.

An MIT demonstration some years back showed transmission across a room. It used a 10MHz radio signal to transmit 60 watts of power (with 45% efficiency) between a pair of antenna coils that were separated by 7 feet. It was hardly iPod-ready, though. The coils were each two feet across.

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ToanP (author)2015-03-09

Actually, the antenna would be 1553.03 miles long; not very practical. Better off using a cord.

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NachoMahma (author)2009-04-08

. Possible, but not very practical. You will better off using a much higher frequency but it's still not going to be very efficient and range is severely limited (inverse square).

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