Fringe Society

In the first part of this series of articles, I posited the ‘why’ of bringing along an EMF meter on an investigation. To concisely summarize the previous results: because they measure electromagnetic fields, of course. What I neglected to mention was the ‘how’ of the matter. Now I plan to take some of the mystery out of the magnetic field—or at least its measurement. Let’s take it from the top, shall we?

Any basic physics book will inform you that EMF refers to the electromotive force. That is just an archaic title for the voltage from a given electrical source—such as a battery. However,
for the paranormal community (and likely the contracting and electrical
communities), EMF has come to be associated with electromagnetic
fields. And for a very good reason: it requires less than half the syllables to say. So we will follow that nomenclature for this article. And what is an electromagnetic field? An EMF is established whenever current flows through a conductor. It’s as simple (or complex) as that. Most often this occurs in standard household wiring, but also transpires every time lightning strikes.

Following that, inversely, if a magnetic field is varying in time it will induce a current through a coil. This is how the standard single/tri-coil EMF meters operate. To see this in action, simply plug in a dynamic microphone and place it in close proximity to active AC wiring. Provided that microphone/soundcard/amplifier does not filter out 60Hz (or 50Hz) you should hear a low frequency hum. Congratulations, you have just made a rudimentary EMF detector. This
works due to the EMF inducing a current in the wire coil of this
variety of microphone and subsequently generating a voltage. Notice
that (for a straight wire instance) the EMF is at a maximum amplitude
perpendicular to the AC wiring and by adjusting the angle of the
microphone relative to the wiring the ‘volume’ rises and falls. This is where tri-coil/tri-field meters have the advantage—proper alignment is less of an issue.

Similar in principal to the coil EMF detector is the fluxgate magnetometer. Put the coil in the aforementioned design onto a ferrous toroid (a doughnut shaped piece of magnetically ‘conductive’ material.) To this, add another coil and attach this to DC voltage source. This will create a coupled magnetic field between the two coils. Provided
that the ferrite core is not operating near saturation (the point at
which an increase in coil magnetic field yields limited increase in the
overall system) the coil on the reception side will be able to read in a
much weaker EMF. The main drawback to both of these setups
is that unless the magnetic field is varying in time, they are
incapable of perceiving it. One method of discovering a potential DC source is to vary the field spatially over time. Yes,
just move the meter back and forth repeatedly at a vigorous rate (of
course, do not neglect the force of acceleration acting upon on analogue
meter…and moving the needle.) Of course there is a more elegant solution to this.

A gauss meter detects both AC and DC magnetic fields. It does this by relying on a linear Hall or other magnetic field sensing semiconductor technology. The solid state semiconductor physics behind a hall-effect sensor are beyond the scope of this article. But
the gist of the matter is that when a magnetic field is applied to a
piece of specially treated semiconductor material, it allows a current
to flow. If the voltage is proportional to the magnetic
field intensity, you have a linear hall-effect sensor that can be
calibrated to register the precise field amplitude. Other examples simply switch on and off over a certain range of field intensity. The magnetic sensors utilized for security door alarms function in this manner.

Gauss meters are effective for both DC and AC fields so they should be used in conjunction with EMF meter. If
the gauss meter goes off while the EMF meter is steady, it implies one
of two things: either the field is nearly static (DC) or the field is
varying at a rate that is much higher than the EMF meter is intended to
operate and is filtered out. Remember that most EMF meters are designed for operation at 60Hz, although models vary greatly. If your EMF meter has a relatively wide frequency response, it likely indicates a DC field. What does a DC field indicate in the paranormal? Not much as far as the spirits and hallucination-inducing time-varying magnetic-fields are concerned. Perhaps the UFO community can point me towards a suggestion.

Additional References:

http://www.who.int/peh-emf/about/WhatisEMF/en/

http://www.zen22142.zen.co.uk/Circuits/Misc/emf.htm

http://www.zen22142.zen.co.uk/Circuits/Testgear/emmeter.htm

http://www.physics.uq.edu.au/people/ficek/pdfs/ph3050.pdf

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/hall.html

http://micro.magnet.fsu.edu/electromag/java/faraday2/