Electromagnetic fields are fields related to but not the same as electrical fields and magnetic fields. It is a property of space caused by the motion of an electric charge.
Electric fields are created by differences in voltage between stationary charges. Magnetic fields are created when electric current flows. A changing magnetic field also produces an electric field. The interaction of electric and magnetic fields produces an electromagnetic field, which has its own existence in space apart from the charges involved. An electromagnetic field can sometimes be described as a wave that transports electromagnetic radiation.
Electromagnetic fields (EMF) are generated in the vicinity of power lines, mobile phones, mobile phone towers, broadcast towers and similar transmitters. Scientific evidence does not demonstrate a causal link between typical exposures to EMF and adverse health effects, including leaukaemia in children. However it is advisable to avoid heavy exposure to EMF if possible.
Technically, the term “electromagnetic field” (EMF) refers to all fields throughout the electromagnetic spectrum. In common usage, however, the term usually refers to so-called extremely low-frequency nonionizing radiation fields—those fields below 300 Hertz (Hz)—and often only to those fields in the 50 to 60 Hz range, which are also known as power-frequency EMFs. These fields induce currents within the human body, which if sufficient can produce a range of effects such as heating and electrical shock, depending on their amplitude and frequency range.
== Units and Measures ==
Electric fields exist whenever a positive or negative electrical charge is present. They exert forces on other charges within the field. The strength of the electric field is measured in volts per metre (V/m). Magnetic fields arise from the motion of electric charges. The strength of the magnetic field is measured in amperes per meter (A/m); more commonly in electromagnetic field research, scientists specify a related quantity, the flux density in microtesla, (µT) or in millitesla (mT) instead.
== References ==
http://www.who.int/peh-emf/about/WhatisEMF/en/ http://www.ehow.com/facts_5911526_definition-electromagnetic-field_.html http://www.answers.com/topic/electromagnetic-field
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