We’ve all seen them on Youtube, the people (usually young or young-in-the-head guys) who wander around a supposedly haunted location with their trusty EMF detector. It beeps, they jump and exclaim “Whoa DUDE! BRO! Check it out! It’s like a 10!”. Instead of science-minded ghost investigators, you’re stuck with Bill and Ted, and this adventure is not remotely excellent. In fact, it sucks.
So what are these shows doing wrong, besides shredding the English language and being casually misogynistic? First and foremost, the actors have absolutely no idea what the meter does, but they also don’t seem to know why they are using it, or even how to properly operate it.
What is an EMF Detector?
An EMF detector (or field meter) is an electro-magnetic frequency measurement device. It is also basically an antenna, and can display electromagnetic wave measurements in:
volts per meter (V/m) – usual for electricity,
milliwatts per square meter (mW/m2) – usual for radio waves,
milliGauss (mG) – usual for magnetism,
nanoTesla (nT) units.
most meters also measure the electromagnetic radiation flux density (DC fields) or the change in an electromagnetic field over time (AC fields), essentially the same as a radio antenna, but with different detection characteristics.
Why do investigators use them?
You will hear skeptics argue that we cannot possibly know that EMF detectors find ghosts, and they may be right. But they do let us set a baseline for a location while noting unexplained “hotspots” where no high electromagnetic field should be. Then, during the investigation we know if a significant spike has happened. If a spike is noted, and there is no obvious cause, it may be one possible indicator that a ghost is present.
The second reason may be even more important. EMF meters show us if a high level of electrical activity is occurring in the environment, giving a possible explanation for why people are seeing or hearing strange things. Very high EMF levels can cause brain wave changes, including insomnia, itching, dizziness, and memory problems.
How do you use an EMF meter?
This is very important: you use an EMF detector to measure electricity and magnetism on objects only. You will not typically wave it about in the air trying to find a ghost. Even if we knew for certain that ghosts carry a strong electromagnetic force, that would take a long time.
Air will rarely hold an electric charge, the exception being something like a thunderstorm, but even then the electricity is generated in a cloud (an object) and meets the earth (an object) or another unlucky earthbound object…like you.
So, with rare exception, stick to measuring objects like walls, tables, electronics, etc. A reading of under than 6 mW or so is unremarkable in any object or structure. You should expect a reading of under 20 mW for an outlet or a wall covering electrical wiring. Here are some other limits:
natural electromagnetic fields (like those created by the sun): 200 V/m
power mains (not close to power lines): 100 V/m
power mains (close to power lines): 10,000 V/m
electric trains and trams: 300 V/m
TV and computer screens: 10 V/m
TV and radio transmitters: 6 V/m
mobile phone base stations: 6 V/m
radars: 9 V/m
microwave ovens: 14 V/m
What would be remarkable?
A reading of 20 on an empty wooden chair. But that rarely happens, even in a haunted location. You are looking for either spikes or high readings in electricity (or less frequently magnetism) which are unexplainable. Cell phones, radios, outlets, etc. will give off relatively high readings, so make sure you are measuring the right object.
If electricity is not in the air, why do I sometimes feel it?
Electricity only comes in one flavor, but we differentiate it based on whether it is dynamic (where one object uses a conductor to get to an oppositely-charged object) or static (energy is released directly to another, oppositely-charged object).
Hopefully you don’t have a ton of intimate experience with conducted, dynamic electricity.
With static electricity, for example when you are standing on a mountaintop before a storm, and your hair stands up (again, don’t do this on purpose). That means you are about to be struck by lightning, my friend. Run!
While the ground typically carries a slight negative charge, a storm cloud above it will make it change to a positive charge. The large negative charge in the middle of the storm cloud repels negative charges on the ground underneath the storm, causing the ground and any objects (or people) on the ground directly underneath the storm to become positively charged.
The negatively charged bottom of a thunderstorm cloud is attracted to these positively charged particles along the ground (including the hair on your head). As the differences in charges continue to increase, positively charged particles rise up tall objects such as trees, houses, and telephone poles—and people. And their hair.
Lightning is an example of static electricity. With all static electricity, there is a buildup of electrical charges on the surface of an object or material (in the case of lightning, the buildup is in a cloud) which can discharge onto an object with the opposite charge.
On a smaller scale, like a pair of socks, if material is pulled apart or rubbed with another material (especially in dry air), positive (+) charges collect on one material and negative (−) charges on the other. The friction causes the electrons from one object to jump ship and go to the other object.
Remember that electrons carry a negative charge, so the more there are on an object, the more negatively charged it gets. And objects losing electrons actually become more positively charged. Opposites always attract to create a neutral charge, so when a positively-charged sock meets a negatively charged sock, they will cling together and have potential electric energy in that bond.
This dissipates with time, but pull them apart just after they’ve met and you might even see a spark. Doing this discharges the potential energy. The crackling comes from the sticky surface electrons being yanked away from each other. This electricity can be as much as 12,000! But…it’s still not in the air.
Fun Fact: Dryer sheets pre-empt static electricity by releasing positively charged particles that satisfy the cravings of negatively-charged surface atoms on your laundry.