Electric Field, Magnetic field, electromagnetic field?

Invisible and intangible, an electromagnetic field is derived from the combination of an electric field and a magnetic field. Most often these two fields are alternative, that is to say they oscillate constantly. Like any wave, electromagnetic fields propagate in space.ย 

Electromagnetic waves serving technology
Fields of applications of electromagnetic waves are very large and modern technologies regularly use them for, among others, convey information. Electronics has learned to manage their amplitude, that is to say the intensity with which they are issued, and their frequency, the number of oscillations they perform every second, to distinguish a program from another and let them carry information. Radio, television, mobile telephony, WiFi and other communication systems are based on this principle. Typically high frequencies are reserved for such uses. It also speaks of spectrum for their associate the notion of transmission. For extremely low frequency fields, such as those generated by power lines, the electric field and magnetic field are independent and act separately.ย 

The electric field is related to the charges….ย 
An electric field is associated with the presence of a voltage. For example, a 220 volt sector generates an electric field in its immediate environment. If a lamp is connected to it, it is also energized and in turn creates an electric field, even if it remains off. Its value is proportional on the one hand to the voltage (in volts) and secondly to the distance from the field source (in meters). It is therefore natural that the value of an electrical field is noted in volts per meter (V / m). This unit lets us sense that as the voltage is higher and the distance short, the higher the electric field increases.

โ€ฆ The magnetic field depends on their movement
The magnetic field, in turn, is directly generated by the current, this is, the movement of electrical charges. If no current flows, as in the previous case, no magnetic field is created: our โ€˜lamp offโ€™ will therefore generate no magnetic field. However, once it is on, current flows through the wire that connects it to the plug, in its filament, etc. This is an electron displacement, and then it occurs a magnetic field. It is proportional to the current intensity involved in amperes and, as for the electric field, inversely proportional to the distance. His unit will be by the ampere meter, denoted A / m.
Note that it is usually preferred unit of magnetic flux: tesla and especially its subdivision, the microtesla noted ยตT.

Wich devices produce electromagnetic waves?

All electrical devices such as TVs, game consoles, induction cooktops, microwave ovens, mobile phones, the Baby-phone, cell phone, smartphone, walkie-talkie, the RFM phone masts or TV, radio identification RFID, tablets, PCs and laptop computers, GPS, home automation, routers, WIFI, WIMAX, Bluetooth technology, radar antennas for boats and aircraft, or parabolic antennas rakes roofs, hybrid or electric …… produce electromagnetic waves that may disrupt human well-being.