Wireless charging for small devices like smartphones and electric toothbrushes is a form of wireless power transfer, but it operates over very short distances using a principle called electromagnetic induction.

• Transmitter and Receiver Coils: The charging pad (transmitter) contains a coil of wire, and the device being charged (receiver) has a similar coil.

• Magnetic Field Generation: When electricity flows through the transmitter coil, it creates a magnetic field.

• Induced Current: When the receiver coil is placed in close proximity to this magnetic field, the field induces an electrical current in the receiver coil, which then charges the device's battery.

This technology is highly efficient and safe, but only over very short, controlled distances (a few millimeters to centimeters). It is not a viable technology for transmitting the massive amounts of power required to run a city or factory.