What are electromagnetic fields ( EMFs) ?

Definition

An electromagnetic field (also called EMF or EM Field) is a physical field produce by moving electrically charged objects. The field can be viewed as the combination of an invisible Electrical Field and a Magnetic Field of force.

Electric Field:

Electric Field is produced by stationary charges. Electric Fields are created by difference in voltage; the higher the voltage, the stronger the electric field at a given distance.
Their strength is measured in Volts per metre (V/m)
An electric field can be present even when a device is switched off.
Field strength decreases with distance from the source.
Most building materials shield electric fields to some extent.

Magnetic Field:

Magnetic field are created when electric current flows; the greater the current, the stronger the magnetic field.
Their strength is measured in amperes per meter (A/m). Commonly, EMF investigators use a related measure, flux density (in microtesla (µT) or millitesla (mT) instead.
Magnetic fields exist as soon as a device is switched on and current flows.
Field strength decreases with distance from the source.
Magnetic fields are not attenuated by most materials.

The basic of frequency and wavelength

One of the main characteristic which define an EMF is its frequency or its corresponding wavelengths. Fields of different frequencies interact with the body in different ways. One can imagine electromagnetic waves as series of very regular waves that travel at an enormous speed, the speed of light. The frequency simply describes the number of oscillations or cycles per second, while the term wavelength describes the distance between one wave and the next.

the higher the frequency, the shorter the wavelength
the shorter the frequency, the higher the wavelength

The standard unit of EMF is the hertz abbreviated Hz. Larger unit are often use as follows:

A frequency of 1000 Hz is one kilohertz (kHz)
A frequency of 1000 kHz is one megahertz (MHz)
A frequency of 1000 MHz is one gigahertz (GHz)

The wavelength of EMF is related to frequency.

The Wavelength is denoted by λ. The Wavelength Formula of any wave is given by

λ = v/f

Where,

V= wave speed

f = frequency

The Wavelength is expressed in m, velocity is expressed in m/s, frequency is expressed in Hz.

EMFs are typically group into two categories base on their frequency.

Non-ionizing : low level radiation which is generally perceived as harmless to human.
Ionizing : high level radiation which has the potential for cellular and DNA damage.

Sources of Electromagnetic field

EMFs are generated by natural phenomena like the Earth magnetic field but also by human activities, through the use of electricity.

Electromagnetic fields are present everywhere in our environment but are invisible to the human eye. Electric fields are produced by the local build-up of electric charges in the atmosphere associated with thunderstorms. The earth's magnetic field causes a compass needle to orient in a North-South direction and is used by birds and fish for navigation.

Besides natural sources the electromagnetic spectrum also includes fields generated by human-made sources: X-rays are employed to diagnose a broken limb after a sport accident. The electricity that comes out of every power socket has associated low frequency electromagnetic fields. And various kinds of higher frequency radiowaves are used to transmit information – whether via TV antennas, radio stations or mobile phone base stations.

The realm of EM field energy is called the electromagnetic radiation spectrum.

The electromagnetic (EM) spectrum is the range of all types of EM radiation. Radiation is energy that travels and spreads out as it goes – the visible light that comes from a lamp in your house and the radio waves that come from a radio station are two types of electromagnetic radiation. The other types of EM radiation that make up the electromagnetic spectrum are microwaves, infrared light, ultraviolet light, X-rays and gamma-rays.

Types of Electromagnetic fields (EMFs)

We have four types of EMFs each with its own frequency. All four have been linked to important biological effects in the scientific research studies, and each type of EMF is measured with a different kind of test instrument.

AC MAGNETIC FIELD EMF - are the EMF component most often linked to serious health effects – such as childhood leukemia and other cancers – in the research studies. Common sources include power lines, electrical wiring, light fixtures, appliances and most other electrical devices. Wiring errors and stray electricity in pipes can sometimes create surprisingly high levels. Magnetic fields are measured with an ELF* gaussmeter, in units called “milligauss” (mG).

(*Note: “ELF” or “extremely-low-frequency” is the scientific name for the EMF frequency range that includes the 60 cycles-per-second – or 60 Hertz – electricity used in the US and Canada.)

AC ELECTRIC FIELD EMF - ELECTRIC FIELD EMF - ELF Electric Fields have also been linked to important biological effects, but have been studied less in the research. Anecdotally, they are often involved when people feel “sensitive” to electromagnetic sources. Electric fields are usually caused by hidden electrical wiring within walls, by nearby power cords for lamps and devices, and sometimes from overhead power lines. Electric fields induce measurable voltages onto the skin, which are easily detected with a Body Voltage Meter, in units of “AC Volts” (VAC).

RADIO FREQUENCY EMF - Radio Frequency (RF) Fields (including microwaves) have been linked to several kinds of tumors and health problems. RF fields are emitted from many wireless and electronic devices – cell towers, cell phones, cordless phones, TV/radio broadcast towers, Smart Meters, Wi-Fi, wireless computers and components, baby monitors, microwave ovens, radar, etc. In the US, they are usually measured in units of “microwatts per centimeter squared” (μW/cm²).

DIRTY ELECTRICITY - the ELF electric and magnetic fields will also carry some added RF frequencies due to the use of dimmers, fluorescent lights, computers, Wi-Fi, Smart Meters, etc.

What are electromagnetic fields (EMFs)