Ghost hunters link sudden spikes and changes in electromagnetic radiation in a given spot to a ghostly presence, so no paranormal kit is complete without an [[xref:http://www.examiner.com/ghosts-hauntings-in-nashville/ghost-hunting-101-emf-what-it-is-and-why-you-need-to-know|EMF detector|EMF detector]] to measure electromagnetic fields. (Hint: If you’re looking to test this out, a compass will spin in areas of high EMF.) However, household and industrial appliances generate electromagnetic fields, and obstructing these fields will cause a spike on an EMF meter. A paranormal investigator might note such a change and consider it ghostly evidence, when in reality they’re just walking between two fields from other equipment.
Image: Courtesy of [[xref:http://www.ghoulparanormal.com/Equipment.php|Ghoul Paranormal|Ghoul Paranormal]]