Radiofrequency electromagnetic fields (EMF)
Radiofrequency electromagnetic fields (EMF) are a type of non-ionizing electromagnetic radiation found on the electromagnetic spectrum covering the range of frequencies below 300 GHz.
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About radiofrequency EMF
Radiofrequency EMF are invisible waves that travel through space and exert force on charged particles. These waves have been used for many years to transmit information between an antenna and a device without the use of wires.
Radiofrequency signals are transmitted from stations to radio receivers. For example:
- cell towers and mobile phones use radiofrequency to send and receive information allowing us to make a call or to access the internet
- remote controls use radiofrequency to send signals to:
- a garage door to open it
- a car to unlock the doors
- a toy car to make it move
In Canada, specific radiofrequency bands are designated for different applications.
Radiofrequency EMF can also be used in products that serve to heat things. This is known as induction heating or dielectric heating.
Physical properties of radiofrequency EMF
There are 3 main characteristics of radiofrequency EMF:
- Wavelength is the distance between two consecutive peaks or troughs of a wave. Wavelength is expressed in units of distance: metres (m), centimetres (cm) or millimetres (mm).
- Frequency is the number of times a wave goes from peak to peak or trough to trough within a second at a fixed location in space. Frequency is expressed in units of hertz: kilohertz (kHz), megahertz (MHz) or gigahertz (GHz).
- Intensity describes the amount of energy transferred per unit area over a unit of time. It is expressed in units of watts per metre squared (W/m2) or milliwatts per centimetre squared (mW/cm2). The intensity is sometimes referred to as the power density.
The intensity of radiofrequency EMF drops off very quickly from its source.
Sources of radiofrequency EMF
Many every day devices use radiofrequency EMFs to transmit information wirelessly such as:
- smart meters
- Wi-Fi enabled devices
- cell phones and cell phone towers
Other examples of common devices that emit radiofrequency EMF include:
- induction cooktops
- sensing instruments
- measuring instruments
- airport full-body scanners
- Magnetic Resonance Imaging (MRI) machines
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