Electric And Magnetic Fields
Electric and magnetic fields (EMF) occur in nature and wherever electricity flows.
Electric and magnetic fields are present in and around the earth. Thunderstorms produce EMF.
The earth’s magnetic field is the force that causes a compass to always point north. Magnetic fields also result from current or the flow of electricity in a wire; field strength increases as the current increases and decreases as distance from the wire increases.
Magnetic fields are measured in units called gauss or Tesla and typically are reported in thousandths of a gauss, milligauss (mG), or microTelsa.
Electric fields are produced by the presence of voltage or an electrical charge: the higher the voltage, the greater the electric field.
Electric fields are measured in volts per meter.
A lamp that is plugged in produces an electric field even while it is turned off. It will produce a magnetic field only when it is turned on.
Objects such as trees, shrubs and buildings can block electric fields. Magnetic fields, however, are not easily blocked and can pass through most objects.
The strength of both fields declines rapidly as the distance from the wire increases.
Because EMF can be found in nature and because our society relies on electricity, people are exposed to EMF much of the time.