How does a magnetic field induce an electric current?

A magnetic field induces an electric current by changing the magnetic flux through a conductor.

When a conductor is placed in a changing magnetic field, the magnetic flux through the conductor changes. This change in flux induces an electromotive force (EMF) in the conductor, which in turn creates an electric current. This phenomenon is known as electromagnetic induction and is described by Faraday's law of induction.

The magnitude of the induced EMF is proportional to the rate of change of magnetic flux through the conductor. This means that the faster the magnetic field changes, the greater the induced EMF and the resulting current. The direction of the induced current is determined by Lenz's law, which states that the current flows in a direction that opposes the change in magnetic flux that produced it.

Electromagnetic induction has many practical applications, including in generators, transformers, and motors. In a generator, a rotating coil of wire is placed in a magnetic field, and the changing flux through the coil induces an EMF that produces an electric current. In a transformer, two coils of wire are placed in close proximity, and the changing magnetic field in one coil induces an EMF in the other coil. In a motor, the interaction between a magnetic field and an electric current produces a rotational force.