What process takes place in an electric machine when stationary is kept in a time-varying field?

In an electric machine, when a stationary part (such as the armature windings in a motor or generator) is kept within a time-varying magnetic field, the process of electromagnetic induction occurs. This principle is fundamental to the operation of many electrical machines, including transformers, motors, and generators. Here’s what happens during this process:

1. Induction of Electromotive Force (EMF): A time-varying magnetic field means that the magnetic flux through the stationary part changes over time. According to Faraday’s law of electromagnetic induction, a changing magnetic flux through a circuit induces an electromotive force (EMF) in it. The magnitude of this EMF is proportional to the rate of change of the magnetic flux.

2. Current Generation: If the stationary part is a closed loop or part of a larger electrical circuit, this induced EMF will cause a current to flow, provided the circuit is completed. The direction of the induced current is given by Lenz’s law, which states that the current will flow in such a direction as to oppose the change in magnetic flux that produced it. This is a manifestation of the conservation of energy.

### Key Components of the Process:

– Time-Varying Magnetic Field: The magnetic field has to change over time to induce EMF. This can be achieved by either moving a magnet relative to a coil, changing the current in the surrounding coils, or through other mechanisms that result in a change in magnetic flux