Let’s Talk Tech – 2) EMF Detectors

You’ll often seen these being waved around by ghost hunters, as the claim is that ghosts manifest themselves through disturbances in the local electromagnetic field (EMF). Investigators will refer to witnessing spikes in EMF as ghosts try to communicate with them. I won’t go into why they believe this, other than to say that it is often portrayed as direct communication when the needle moves.

So what is EMF? Let’s not panic about something being a human thing that isn’t a natural phenomenon. We find it in the power put out from the Sun, and when that electromagnetic radiation interferes with the Earth’s magnetic field we witness the Aurora Borealis and Australis, very natural events. Yet humans have filled the earth with EMF too. Modern life brings its conveniences, many electrical in nature; WiFi, microwave ovens, and radio waves, etc.

Wherever there is electricity, you will find a corresponding magnetic field. When you study secondary school physics you will be taught those rules you act out with your fingers and thumbs corresponding to the direction of the magnetic field generated in the presence of an electrical current. The facts of this physical phenomenon mean we can have motors, generators, and loudspeakers, etc. Small currents produce small fields, but they can be very large and some suggest that exposure to large EMFs can be detrimental to humans. Think of the controversy around living beneath electric pylons. So it’s no surprise that detectors exist for measuring these invisible fields.

Ghost hunters can sometimes be a superstitious lot, and may prefer a specific piece of kit. On stage I use what some prefer, the Trifield TF2, which is very precise on its ‘standard, magnetic’ setting, displaying a large range accurately up to 100 milligauss (The gauss is the measure of the strength of a magnetic field). The ‘weighted’ setting is to simulate what the EMF would be when you as a person absorb it, so not what you need on a vigil.

As popular and expensive as it is, the audience rarely see the needle move very far unless I’m waving it around, so I know I’m getting a typical reading. If you were to use this on a vigil you should be holding it still, not waving it around though. That’s how you take a baseline reading and are just not measuring false peaks detected by the fields generated by lights and other electrical devices. As a device, it’s great, but would be fairly boring on a hunt.

Is there a cheaper, more exciting alternative? Yup, you can go for what many people call the ‘K-II’ (pronounced ‘K-2’). These devices are often sold under generic names, so if it looks like the one below, it’s likely to be identical inside.

What makes this favoured by ghost hunters? Well, rather than paying for the features and precision of the much more expensive Trifield, what you get is something that responds instantaneously and on a crude scale of five lights from green to red. This makes it quite ‘twitchy’. The slightest thing in the environment around it will cause it to flicker madly. Indeed, flicker so fast that there is no way that the digital readout on the Trifield could display anything readable. Again, if you want to use this, stand still and hold it correctly. Obviously, that ‘twitchiness’ can be seen as its appeal, especially if you’re out to search for the slightest ‘something’ YOU also might be ‘twitchy’ about.

However, you can get one for free if you download the Phyphox app for your mobile phone (https://phyphox.org). It contains pre-made experiments that utilise the sensors your smart phone may have. One experiment is the magnetometer. Start it running and wave it around a little. The specific hardware it uses in your phone is designed to measure the Earth’s magnetic field, which it needs for your compass and the like. As such, it’s very sensitive, if a little difficult to read all three graphs at once, depending on how you hold the phone. Try detecting electromagnetic fields where the wires in the walls are hidden, or something different. It might be worth keep this app in mind for other science experiments you encounter in life.

So go and unpack the world of physics around you. You don’t have to be a ghost hunter to play along, just be curious. It helps to have an inside track on what sort of stuff is out there, which is why I’m running this series of posts.