History of Electromagnetic Induction
– Faraday’s experiment showing induction between coils of wire
– Faraday and Joseph Henry independently discovered electromagnetic induction in the early 1830s
– Faraday’s first experimental demonstration involved wrapping wires around an iron ring
– Faraday observed transient currents when connecting and disconnecting wires to a battery
– Faraday found several other manifestations of electromagnetic induction, such as sliding a bar magnet in and out of a coil of wires
Theory of Electromagnetic Induction
– Faraday’s law of induction makes use of the magnetic flux through a wire loop
– The induced electromotive force (emf) in a closed circuit is equal to the rate of change of the magnetic flux
– Lenz’s law states that the induced current will flow in a direction that opposes the change which produced it
– Exploiting flux linkage by creating a tightly wound coil of wire increases the generated emf
– Faraday’s law is one of the four Maxwell’s equations and plays a fundamental role in classical electromagnetism
Faraday’s Law of Induction and Lenz’s Law
– Faraday’s law of induction uses the magnetic flux through a wire loop to induce an electromotive force (emf)
– The induced emf is equal to the rate of change of the magnetic flux enclosed by the circuit
– Lenz’s law determines the direction of the induced current, which opposes the change that produced it
– Increasing the generated emf can be achieved by creating a tightly wound coil of wire with identical turns
– Faraday’s law and Lenz’s law are fundamental principles in the theory of classical electromagnetism
Faraday’s Law and Relativity
– Faraday’s law describes two different phenomena: motional emf and transformer emf
– Motional emf is generated by a magnetic force on a moving wire, while transformer emf is generated by a changing magnetic field
– Albert Einstein noticed that both phenomena corresponded to a relative movement between a conductor and a magnet
– The outcome of both phenomena is unaffected by which one is moving, leading to the development of special relativity
– Faraday’s law and its applications played a role in Einstein’s understanding of relativity
Electrical Transformers
– When the electric current in a loop of wire changes, it creates a changing magnetic field
– The changing magnetic field induces an electromotive force (emf) in a second wire in reach of the magnetic field
– This induced emf is known as transformer emf
– If the two ends of the second wire are connected through an electrical load, current will flow
– Transformers are devices that utilize the principles of electromagnetic induction to transfer electrical energy between circuits. Source: https://en.wikipedia.org/wiki/Electromagnetic_induction
Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction. Lenz's law describes the direction of the induced field. Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism.
Electromagnetic induction has found many applications, including electrical components such as inductors and transformers, and devices such as electric motors and generators.
