The Electromagnetic Spectrum consists of a wide-range of wavelengths/frequencies over which electromagnetic radiation extends. It is divided into ionizing and non-ionizing radiation. Ionizing radiation, like X-Rays, have very short wavelengths. Devices emitting non-ionizing radiation, like common household appliances to cell phones, have very long wavelengths. Being that energy is inversely related to the wavelength, the shorter the wavelength the more energy is created.
The term Electromagnetic Field (EMF) can be understood as invisible lines of force in the non-ionizing radiation band on the electromagnetic spectrum. EMF can also be used in a broad sense to generally define electric, magnetic and radio frequency fields.
In the extremely low range, such as power lines and the wiring in homes and facilities (Alternating Current), those fields are typically referred to as electric and magnetic fields. These types of fields in the United States move at 60Hz per cycle. Electric fields are present when any source is carrying a potential or voltage and magnetic fields are present anytime current is flowing through a wire.
In the higher range are radio frequency (RF) fields that radiate, such as cell phones, radar, and Wi-Fi. These types of fields are given both a frequency and power density rating. Unlike its counterpart on the low range, there are much clearer standards and regulations through the Federal Communications Commission (FCC) for the use and design of these fields.
While these types of emissions are part of life, there are proven techniques to reduce them substantially whether it be out of health concerns or interference and performance degradation issues with sensitive equipment. Exposure can be excessive when sloppy wiring techniques and code violations are employed by errant electricians. Other elevated EMF exposures can exist when the design process does not include specific considerations to reduce these emissions.