One of the most popular tools used by paranormal researchers is the EMF Detector. An EMF detector measures the levels of electromagnetic energy in a specific area. It is commonly believed that 'ghosts' appear to have an effect on electromagnetic readings. Therefore, researchers seek out readings that appear to be somewhat out of the ordinary and random in occurrence.
To be more specific, these detectors provide the researcher with accurate electromagnetic readings in terms of Gauss, v/m (Volts per meter), and hertz. Common household appliances emit these energies on a daily basis. For instance, the microwave in your kitchen usually emits between 100 KHz to 2.5 GHz. Your television set emits energy, as well as wiring in the walls of your home. Lamps, stereos, computers, they all emit a specific amount of detectable energy. Even humans emit what is referred to as natural electric field. Animals emit the same form of energy. On rare occasions people will appear to be 'invisible' to natural electric readings, but more often than not, they are detectible.
Paranormal researchers, including myself, value collecting energy readings because of the scientific foundation behind such techniques. Every physical manifestation requires a certain amount of energy to exist. Therefore, it is our belief that these energies can be used to detect unseen entities. In many instances, these energies are detected and have been documented. They are unexplained in nature, and a random in occurrence. One moment they are there, the next they are not.