The prime sensory instrument of any ghost investigation is an EMF meter/detector. EMF stands for Electromagnetic Field and is the basis of many theories in ghost research. It is a common theory that spirits disrupt the ambient electromagnetic field in such a way that you can tell one is present by higher than normal readings with the meter. The emf meter, in a sense, is the modern day ghost researcher's tracking device. With the EMF meter it is possible to locate and track energy sources in the environment. The meter will detect fluctuations in electromagnetic fields and low strength moving EMF fields that seem to have no source. There are two broad categories of emf meters; these are AC and DC meters. The most inexpensive ones are designed to measure 60Hz electrical fields across one access which is the standard operating level of any given electrical appliance. The more expensive emf meters can be variable and measure electromagnetic fields that fluctuate outside of normal electonics convention. These meters can also measure across multiple axis and give a more accurate representation of em fields in the area.
Their usage is quite easy. First, they measure em fields in milligauss which is abreviated as mG. Because of this, emf meters are also known as Gauss meters - the word Gauss is named after mathematician Carl Friedrich Gauss.
Before using the EMF as a ghost research tool on an investigation be sure to walk around the area and take initial readings around energy sources such as light poles or electrical outlets to be sure of the readings you receive while scanning the area during the investigation. Most units when purchased come with a manual describing most household and major appliances and their corresponding electromagnetic reading. When using the EMF as a tracking device look for fluctuations of >2.0mG to <7.0mG. Most ghost researchers feel this range is the sweet spot for paranormal activity.
