This paragraph explains some physical definitions and examples of probable sources of emission.
DEFINITION OF ELECTRIC FIELD, MAGNETIC FIELD AND ELECTROMAGNETIC FIELD
| Kind of field | What produce them | Possible shielding | Kind of radiations |
|---|---|---|---|
| Electric | Every device connected at electric socket (even off) | They can be shielded by common material (bricks, wood, metals) | Not Ionisable Radiation |
| Magnetic | They are produced only by working electrical devices | They are not easily shielded (except high conductivity metals, but they are expensive) | |
| Electromagnetic | They are generated by interaction between electric and magnetic fields, we distinguish them in low frequency and high frequencyChe cosa si intende per radiazione elettromagnetica? | ||
What is an electromagnetic radiation?
Electromagnetic radiations are a kind of energy due to electromagnetic interaction, they may spread in vacuum and in the atmosphere. We distinguee them in Not Ionisable radiations and Ionisable Radiation.
DEFINITION OF NOT IONISABLE RADIATION AND IONISABLE RADIATION
| Kind of radiations | Frequency Range | Effects | Examples |
|---|---|---|---|
| Not Ionisable Radiation (NIR) | 0 < f < 300 GHz | Electromagnetic pollution is due to an anthropic origin | Radio, television, mobile phone, radars, visible light |
| Ionisable Radiation (IR) | >300 GHz | They produce the ionization process (creation of atoms and molecules electrically charged) breaking bonds that held molecules in cells | Radiographs |
NIR frequency spectrum is very wide: in it we recognise low frequency fields and high frequency fields.
DEFINITION OF LOW FREQUENCY FIELD AND HIGH FREQUENCY FIELD
| Electromagnetic field | Range di frequenza | Nozioni di fisica | Sorgenti |
|---|---|---|---|
| Low frequency | 0 Hz<f<400 KHz | Electromagnetic and magnetic fields are independent from each other, that remain localized near the generating sources. The field intensity decreases in function of distance. | Power lines, transformation cabins, household appliances
|
| High frequency | 400 KHz<f<300 GHz | High frequency electromagnetic and magnetic fields are related, the existence of one implies the existence of the other and together they constitute the electromagnetic field. | Broadcasting aerials, base stations for mobile telephony, mobile phones, radars, microwaves, amateur radios, radio bridges |
