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 man-made and natural sources generate changing electrical currents and voltages that can cause EMI: automobile ignition systems, cell phones, thunder storms, the
Sun, and the
Northern Lights. EMI frequently affects
AM radios. It can also affect
cell phones,
FM radios, and
televisions.