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Now, humanity can beam 50-60 watts power through 10 centimeter-thick concrete block. Can such wireless power transfer harm us by anyways?

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I'm struggling to find details of the "Electric Vehicle on Electrified Roadway" system described in your link, but I would guess it uses electromagnetic induction so it's generating a magnetic field rather than an EM wave. I'm sure the researchers have been careful to choose frequencies that are not strongly absorbed by humans. A poor choice of frequency would result in an induction furnace and would cook anyone crossing the road :-)

You do need to be careful about strong magnetic and/or electric fields. After all a microwave oven is just a strong electric field and it wouldn't be healthy to live in. However the frequency of a microwave oven is carefully chosen to be strongly absorbed by water, and in general EM radiation isn't strongly absorbed by flesh. Inductive heating relies on the conductivity of the medium allowing eddy currents to be generated, and again I don't think flesh is conducting enough for you to get cooked. However any metal objects, like your wristwatch, could get hot enough to burn you.

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  • $\begingroup$ Nice answer.. But, let me wait for more pin-pointed answers. $\endgroup$ – Schrödinger's Cat Jul 9 '12 at 17:22
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Although details are not given in the article you linked to, wireless energy transfer typically does not use ionizing radiation. It is harmless.

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  • $\begingroup$ A microwave oven use non-ionizing radiation, as does an industrial laser - it doesn't mean it's harmless. $\endgroup$ – Martin Beckett Jul 10 '12 at 4:44
  • $\begingroup$ You are correct. However, microwave ovens and lasers operate at much higher energy density levels than the system in the article. If the question was about wireless power transfer in general, yes, intensity is something to consider. $\endgroup$ – Adam Hunt Jul 10 '12 at 15:18

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