How does wireless charging work?

 

AC energy is coupled inductively in the same way a transformer works.
There is a coil in the device to be charged that receives the AC signal from the charger.

 

There is a coil in the device to be charged that receives the AC signal from the charger.

How is electricity transferred without wire?

 

Magnetic coupling...... The charger is in effect a two-piece "transformer" which only transfers power when the item is installed on its charger...

 

How is electricity transferred without wire?

It is called electromagnetic induction.

 

Here is a pretty good explaination of how it works:

http://powerbyproxi.com/wireless-charging/