what is the principle of resonant coupling

Resonant coupling is a principle in physics and electrical engineering that states that two systems with similar resonant frequencies can transfer energy between them efficiently. This means that if a source of energy is applied to one system, it can induce a resonant response in the other system, allowing energy to be transferred between them. This principle is often used in wireless charging and wireless power transmission, where resonant coupling is used to transfer energy between two coils with similar resonant frequencies.