Wireless battery chargers consist of a transmitter and receiver for transmitting power without connecting cables or wires to the device. A battery can be charged by simply placing the appliance close to a wireless power transmitter or a designated charging station. As a result, the appliance casing can be made completely sealed, even waterproof. Besides the inherent convenience it offers, wireless charging can also greatly enhance reliability, since the charging plug on the side of an appliance can suffer mechanical damage easily, or simply by someone inadvertently plugging in the wrong adapter. The underlying principle behind wireless charging is the well-known Faraday’s law of induced voltage, commonly used in motors and transformers.