Induction Chargers, i.e., your electric toothbrush.

Ever seen how the charging station of an electric toothbrush has no copper contacts? How does it charge the brush? This is a good example of inductive charging.

This way of charging up appliances is becoming more and more common. Many new types of i-whatevers and cellphones can be charged from sleek, mysteriously-connection-free black slabs.

An induction charger.

How it works

The charger has an internal coil. This creates an alternating magnetic field in proximity to the charger. Any appliances or electronics that are induction chargable will also have an internal coil that will be linked to the magnetic field. Current will flow. The appliance will charge.

This type of charging is advantageous over cables in that it provides complete isolation, so it reduces the chance of electrocution. The appliance being charged can be sealed off or even completely waterproof.

Some medical devices that have been implanted can be charged without having to be removed. Some prototype electric cars use induction charging stations. Wireless headsets, PS3 consoles, wireless mice, 等等。。。

Is this something a person can build? A crude kind (here). Crude’s the point really…

Tesla's i-Phone charger. It suffered from copper losses, amongst other small problems.

But the idea of transporting electricity through air is not new – Nikola Tesla experimented with the concept and imagined a future with power being moved over huge distances with no wires.

But the idea might be making a comeback.