Faraday's law of electromagnetic induction is a fundamental principle in electromagnetism that states that a changing magnetic field can induce an electromotive force (EMF) in a closed loop circuit. This phenomenon, known as electromagnetic induction, forms the basis for various technologies, including transformers and electric generators.

For example, consider a simple loop of wire placed near a changing magnetic field. As the magnetic field changes, it creates a flux through the loop, which induces an EMF. This induced EMF can then drive a current to flow through the wire.

Transformers, one of the applications of electromagnetic induction, are used to increase or decrease the voltage in AC circuits. They consist of two coils of wire, a primary and a secondary, wound around a single core. When an alternating current passes through the primary coil, it creates a changing magnetic field that induces an EMF in the secondary coil. This allows for efficient transfer of electrical energy between circuits.

Electric generators also rely on Faraday's law to produce electricity. They work by rotating a coil of wire within a magnetic field. As the coil moves, the magnetic field through the coil changes, causing an induced EMF. This induced EMF drives a current, which can be used to power electrical devices.