I believe it's a bunch of tiny iron filings suspended in some sort of oil, squished between two sheets of plastic. The iron moves in relation to the magnetic field, letting you visualize magnetic field lines.
This isn't X-Rays, it's magnetic viewing film. You can buy it on amazon for around $10 here
I strongly suggest you pick up some magnetic test paper. It is a cheap and a lot of fun.
I DIY’d a vertical magnetic wireless iPhone charger for my wall.
In my case, I used a magnetic viewing film on my Pitaka MagEz Wireless Charger and some translucent paper to mark where the magnets were.
Then I took apart my cheap wireless charger, and placed tiny neodymium magnets inside the plastic cover.
You can do the same, just use the magnetic viewing film on the iPhone 12. Test it out to make sure you’ve oriented the magnets correctly before you make any permanent changes to your wireless charger.
It‘a pretty easy, and it’s super convenient to just slap my phone on the wall next to my bed every night.
I found some for $9 on Amazon This would have been cool to see in science class.
I agree that the price seems pretty cheap for something that I assume could be reused an unlimited number of times.
Actually it looks like amazon has it for a little cheaper, even:
You can get magnetic film from Amazon and it will show you where the magnets are. Link
https://smile.amazon.com/Magnetics-Green-Magnetic-Field-Viewing/dp/B000UV6ZPS
I have some, it's pretty cool!
They sell it on amazon. "magnetic field viewing film" https://www.amazon.com/Magnetics-Green-Magnetic-Field-Viewing/dp/B000UV6ZPS
That's an interesting thought... kind of curious to see what it would do. I think you'd only run into issues very close to or on top of a magnet. If it were me, I would try positioning your prints in a part of the bed with the least magnets-- they are around the edge and a few in the middle. Study the pics here or get yourself a piece of magnetic viewing film to make it easier to see where those spots are.
CMS Magnetics 4" x 6" Green Magnetic Field Viewing Film
it was less than $10 and totally worth it.
So, interestingly, you can actually see magnetic fields in THREE dimensions. Yeah, 3d. How so? They're called ferrocells. Here's an imgur album http://imgur.com/gallery/xQRYH
I can actually explain how this happens, too. It's called "Field incommensurability." Take a north and south pole of a magnet, they're "located" there right? Nope, if you could split the magnet in half there would be TWO north and TWO south poles on each side of the magnet. Split it again, there will be a north and south pole on each piece, every single time. This is an example of field incommensurability.
Now, when you take that magnetic viewing film and place two magnets side by side you'll see the white plane self-center itself around the two magnets.
What's actually happening is that when a magnet reaches another magnet and comes in contact, it becomes ONE entity - one magnet. So at that end with the singular one it's actually going to a new "end" of the magnet, as the entirety of the magnet becomes one big, long magnet.
Field incommensurability is where fields are non-point-specific, and are not LOCATED at somewhere, they are FORCED there, or are a pressure mediation to that spot. Think of it like water flowing down a hill, it's forced to be at that location.
Found one on Amazon for $9
CMS MAGNETICS 4" x 6" Green Magnetic Field Viewing Film, Fun! https://www.amazon.com/dp/B000UV6ZPS/ref=cm_sw_r_cp_apa_7ZwbCb2Q6C9AD
Jesus f'in christ, people. $8.76 for an 4"x6" film with 2 day prime shipping.