In electrical engineering, two conductors are said to be inductively coupled or magnetically coupled when they are configured in a way such that change in current through one wire induces a voltage across the ends of the other wire through electromagnetic induction. A changing current through the first wire creates a changing magnetic field around it by Ampere's circuital law. The changing magnetic field induces an electromotive force (EMF) voltage in the second wire by Faraday's law of induction. The amount of inductive coupling between two conductors is measured by their mutual inductance.
Example of inductive coupling, 1910. The bottom coil is connected to AC power. The alternating magnetic field through the top coil induces current in it which lights the lamp.
Power transformer transfers power from one winding to the other by inductive coupling
Antenna transformer inductively couples antenna of AM radio station to transmitter
clamp ammeter measuring current by inductive coupling
Electromagnetic interference
Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. The disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data. Both human-made and natural sources generate changing electrical currents and voltages that can cause EMI: ignition systems, cellular network of mobile phones, lightning, solar flares, and auroras. EMI frequently affects AM radios. It can also affect mobile phones, FM radios, and televisions, as well as observations for radio astronomy and atmospheric science.
Electromagnetic interference in analogue TV signal
Interference by 5 GHz Wi-Fi seen on Doppler weather radar