The phenomena also occurs in nature. For example, the earth is a giant magnet surrounded by its own magnetic field. And strong electrical fields are created during thunderstorms. Lightning is a result of this electricity being discharged. Power lines, electrical wiring, and appliances produce low-frequency electric and magnetic fields.
Electrical fields are basically regions containing forces which repel or attract charges.
Voltage on any wire creates an electrical field around the wire. Plugging an ordinary lamp into an electrical outlet causes voltage to enter the cord which then emits an electrical field. When the lamp is switched on, current flows through the cord, and the cord then emits a magnetic field as well. The intensity of an electrical field depends on the voltage in the conductor. Electrical fields inside most houses are usually not increased by nearby powerlines because trees, shrubs, and building materials shield the house and thus reduce the strength of the fields.