Have you ever watched a ghost hunting show on television and noticed the people looking for the ghosts use a handheld device that looks kind of like a stud finder? The device lights up, apparently indicating spiritual activity in a certain part of a building and everyone gets really excited. The name of the little device those ghost hunters were using is a K2 (or K-II) meter or EMF meter.
I know a lot of you are wondering if it is some magical device made especially to detect wayward spirits. The answer is a resounding no. A K2 meter is actually designed to detect electromagnetic fields, kind of like how you use a voltmeter to read electrical activity in a circuit, only a K2 meter reads electromagnetic fields in the air. The device is actually commonly used to diagnose problems with electrical wiring in buildings.
If you're like me you're wondering if all those times a ghost hunter sees a spike in he K2 meter it's just the meter picking up a problem with the building's wiring. It's a valid concern and something skeptics criticize ghost hunters for. In fact, other devices like cordless phones, radios, etc can put off electromagnetic frequencies that can create a spike on a K2 meter.
There are ghost hunters who refuse to use K2 meters because they question the validity of any readings from the meter as far as it pertains to the paranormal. It seems to me that unless an electrician goes through a building and inspects the wiring first, any readings using a K2 meter could easily be irrelevant.
Still, there are those who continue to see the K2 meter as a vital instrument when it comes to ghost hunting. These people claim that ghosts put off electromagnetic fields, meaning a K2 meter can pick up their presence. It is true the several well-documented hauntings have correlated with high electromagnetic activity in a building, but one basic lesson of science is that correlation does not show a causal relationship. Some people theorize that high electromagnetic activity can actually cause people to hallucinate or experience false sensory stimulation.