An electric field is an invisible force field created by the attraction and
repulsion of electrical charges (the cause of electric flow), and is measured in
Volts per meter (V/m).
The intensity of the electric field decreases with distance from the field
A static electric field (also referred to as electrostatic field) is an
electric field that does not vary with time (frequency of 0 Hz). Static electric
fields are created by electrical charges that are fixed in space. They are
different from fields that change over time, such as electromagnetic fields
generated by appliances using alternating current (AC) or by cell phones etc.
When a bedside lamp is plugged in, i.e. connected to the electricity network
through the socket, there is only an electric field. The electric field can be
compared to the pressure inside a hosepipe when it is connected to the water
supply system and the tap is closed. The electric field is linked to the tension
whose unit is the Volt. It is generated by the presence of electric charges and
is measured in Volts per metre (V/m). The greater the power supply of the
appliance, the greater the intensity of the resulting electric field.
When the lamp is switched on, i.e. when the current goes through the
alimentation cable, there are both an electric and a magnetic field. The
magnetic field results from the passage of current (i.e. the movement of
electrons) through the electric wire. In the example with the hosepipe, the
magnetic field would correspond to the passage of water through the pipe. The
unit of the magnetic induction field is the Tesla (T). However, the magnetic
fields that are commonly measured are within the range of the microtesla (µT)
that is to say one millionth of a Tesla. Another unit sometimes used is the
Gauss (G). One Gauss is the equivalent of 100 microtesla.
When switched off (left): electric field
When switched on (right): electric and magnetic field