This demonstration never fails to be a crown pleaser. However, this one was quite a bit more practical.
The idea of transmitting energy wirelessly isn’t new. For almost two centuries, scientists have known that rapidly changing magnetic fields, such as those produced by an alternating current flowing through a wire, can induce an electric current in another wire. That’s how the coils inside power transformers transmit energy from one coil to another without touching. But this form of induction usually works efficiently only when the two coils are very close to each other.