Physics: Faraday's law

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Faraday's law Form: ε = -dΦ/dt In electromagnetism, Faraday's law of induction describes how a changing magnetic field can induce an electric current in a circuit.

Commentary

Faraday's law Form: ε = -dΦ/dt In electromagnetism, Faraday's law of induction describes how a changing magnetic field can induce an electric current in a circuit. What Faraday's law means This equation relates fundamental physical quantities. Every time physicists apply this formula, they're building on a breakthrough that transformed how we understand reality. Deep dive: Faraday's law ε = -dΦ/dt In electromagnetism, Faraday's law of induction descr ibes how a changing magnetic field can induce an electric current in a circuit. This phenomenon, known as electromagnetic induction, is the fundamental operating principle of transformers, inductors, and many types of electric motors, generators and solenoids. In the literature, however, Faraday's law is used to refer to two closely related but technically distinct statements, either of which can be used to explain the phenomenon of induced current described above. One is the Maxwell–Faraday equation, one of Maxwell's equations, which states that a time-varying magnetic field is always accompanied by a circulating electric field. This law applies to the fields themselves and does not require the presence of a physical circuit. The other is Faraday's flux rule, or the Faraday–Lenz law, which relates the electromotive force (emf) around a closed conducting loop to the time rate of change of magnetic flux through the loop. This rule can be derived from the first in specific context of a closed circuit. The flux rule accounts for two mechanisms by which an emf can be generated. In transformer emf, a time-varying magnetic field induces an electric field as described by the Maxwell–Faraday equation, and the electric field drives a current around the loop. In motional emf, the circuit moves through a magnetic field, and the emf arises from the magnetic component of the Lorentz force acting on the charges in the conductor. Historically, the differing explanations for motional emf and transformer emf posed a conceptual problem, since the observed current depends only on relative motion, but the physical explanations were different in the two cases. In special relativity, this distinction is understood as frame-dependent: what appears as a magnetic force in one frame may appear as an induced electric field in another.

Sources: Wikipedia