wireless phone charging

Inductive charging, also known as wireless charging or cordless charging, is a type of wireless power transfer. It uses electromagnetic induction to provide electricity to portable devices. Inductive charging is also used in vehicles, power tools, electric toothbrushes, and medical devices. The equipment can be placed over an inductive pad free of any electrical contacts such as a dock or plug.
Inductive charging transfers energy through inductive coupling: alternating current passes through an induction coil, generating a fluctuating magnetic field, which creates an induced alternating electric current in a nearby secondary coil. The alternating current can be rectified to a direct current which charges a battery or provides operating power.
Greater distances between sender and receiver coils, such as those required for wirelessly charging electric vehicles, can be achieved with resonant inductive coupling. The alternating current of the system can use a resonance frequency tuned with capacitors to create a transmitter and receiver LC circuit with a specific resonance frequency. The frequency is chosen depending on the distance desired for optimal efficiency, and as of 2025 the frequency is commonly 85 kHz. Some systems use inductive loops made of Litz wire surrounding ferrite cores. Charging efficiency is sensitive to lateral, longitudinal, and vertical misalignment. Misalignment of more than 3 cm (1.2 in) can severely lower power transfer. Some systems align their coils by having the receiver coils mounted on a movable arm that can be lowered closer to the transmitter coils, for example it can be lowered from the underside of a truck closer to a transmitter coil on the ground.

View More On Wikipedia.org