Knowledge Base
Electromagnetic Induction
The process by which a changing magnetic field generates an electromotive force (voltage) in a conductor, the fundamental operating principle of transformers.
Electromagnetic induction is the fundamental physical phenomenon that makes transformers, generators, and many other electrical devices possible. Discovered by Michael Faraday in 1831, it describes how a changing magnetic field creates an electric field, inducing a voltage (electromotive force, or EMF) in nearby conductors.
Faraday's Law
Faraday's law states that the induced EMF in a coil is proportional to the rate of change of magnetic flux through the coil:
EMF = −N × (dΦ/dt)
Where N is the number of turns and Φ is the magnetic flux. The negative sign (Lenz's law) indicates that the induced EMF opposes the change that produces it.
Role in Transformers
In a transformer, alternating current in the primary winding creates a continuously changing magnetic field in the core. This changing field passes through the secondary winding, inducing a voltage proportional to the turns ratio.