Tesla is cool. Not the cars, but the scientist, Nikola Tesla. He invented wireless charging in the 1800s. He built the Tesla tower in 1904 (figure 1). The structure was 187 feet tall, and before it radiated the entire field around it and destroyed itself like a firework, it successfully transferred electricity wirelessly 30 feet away. Cool.

Since then, wireless charging has been available, but not very popular. It has been very inefficient, expensive, unsafe and impractical. But now you’re starting to see it everywhere in toothbrushes, watches, phones, headsets and other consumer electronics. It’s basically the same technology that Tesla invented over a hundred years ago. One electrical coil creates a magnetic field which is picked up by a second electrical coil, and then power is transferred wirelessly. It’s called “inductive coupling” or “magnetic resonance coupling.”