Faraday's law of electromagnetic induction states that a changing magnetic field within a closed loop induces an electromotive force (EMF) in the wire. This means that if the magnetic field around a conductor changes, it generates an electric current in that conductor. The strength of the induced EMF is directly proportional to the rate of change of the magnetic field. This principle is fundamental in many technologies, including electric generators and transformers. It explains how mechanical energy can be converted into electrical energy and vice versa, playing a crucial role in the generation and distribution of electricity.