Electromagnetic fields (EMF)
According to WHO, (EMF) Electromagnetic fields are called‘non-ionizing radiations’
What is - Electromagnetic fields (EMF)
The Human-made sources of electromagnetic fields include various kinds:
Higher frequency radiowaves or Radio frequency(RF) - used to transmit information – whether via TV antennas, radio stations or mobile phone base stations.
Low frequency electromagnetic fields.The electricity that comes out of every power socket has associated low frequency electromagnetic fields.
The alternating electric field would drive the electrons in the molecules to oscillate; and the kinetic energy of the oscillation would dissipate into heat and then increase the temperature of the tissue.
The electromagnetic spectrum:
Besides natural sources the electromagnetic spectrum also includes fields generated by human-made sources:
Man-made sources of electromagnetic fields that form a major part of industrialized life - electricity, microwaves and radiofrequency fields – are found at the relatively long wavelength and low frequency end of the electromagnetic spectrum.
Electric fields are created by differences in voltage: the higher the voltage, the stronger will be the resultant field.
Magnetic fields are created when electric current flows: the greater the current, the stronger the magnetic field. An electric field will exist even when there is no current flowing. If current does flow, the strength of the magnetic field will vary with power consumption but the electric field strength will be constant.
What are the main sources of low, intermediate and high frequency fields?
(ELF)extremely low frequency fields:
The time-varying electromagnetic fields produced by electrical appliances are an example of extremely low frequency (ELF) fields. ELF fields generally have frequencies up to 300 Hz.
(IF) Intermediate frequency fields with frequencies from 300 Hz to 10 MHz
(RF) Radiofrequency fields (also called high frequency) with frequencies of 10 MHz to 300 GHz.
Elaboration:
High frequencies (Radiofrequency)
High frequencies (Radiofrequency) produce microwave radiation which can be harmful
Low frequency:
Electrical power supplies and appliances are the most common sources of low frequency electric and magnetic fields in our living environment. The electricity that comes out of every power socket has associated low frequency electromagnetic fields.
Significance:
Both Low frequency and high frequency electromagnetic waves affect the human body in different ways.
The high and low frequency produce the Electomagnetic fields (EMF) , according to WHO, EMF are called ‘non-ionizing radiations’.They are harmful to health.
Microwave frequency bands |
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Letter Designation |
Frequency range |
Wavelength range |
Typical uses |
1 to 2 GHz |
15 cm to 30 cm |
military telemetry, GPS, mobile phones (GSM), amateur radio |
|
2 to 4 GHz |
7.5 cm to 15 cm |
weather radar, surface ship radar, and some communications satellites (microwave ovens, microwave devices/communications, radio astronomy, mobile phones, wireless LAN, Bluetooth, ZigBee, GPS, amateur radio) |
|
4 to 8 GHz |
3.75 cm to 7.5 cm |
long-distance radio telecommunications |
|
8 to 12 GHz |
25 mm to 37.5 mm |
satellite communications, radar, terrestrial broadband, space communications, amateur radio |
|
12 to 18 GHz |
16.7 mm to 25 mm |
satellite communications |
|
18 to 26.5 GHz |
11.3 mm to 16.7 mm |
radar, satellite communications, astronomical observations |
|
26.5 to 40 GHz |
5.0 mm to 11.3 mm |
satellite communications |
|
33 to 50 GHz |
6.0 mm to 9.0 mm |
satellite communications, terrestrial microwave communications, radio astronomy, automotive radar |
|
40 to 60 GHz |
5.0 mm to 7.5 mm |
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50 to 75 GHz |
4.0 mm to 6.0 mm |
millimeter wave radar research and other kinds of scientific research |
|
60 to 90 GHz |
3.3 mm to 5 mm |
UHF transmissions |
|
75 to 110 GHz |
2.7 mm to 4.0 mm |
satellite communications, millimeter-wave radar research, military radar targeting and tracking applications, and some non-military applications |
|
90 to 140 GHz |
2.1 mm to 3.3 mm |
SHF transmissions: Radio astronomy, microwave devices/communications, wireless LAN, most modern radars, communications satellites, satellite television broadcasting, DBS, amateur radio |
|
110 to 170 GHz |
1.8 mm to 2.7 mm |
EHF transmissions: Radio astronomy, high-frequency microwave radio relay, microwave remote sensing, amateur radio, directed-energy weapon, millimeter wave scanner |