If you were around tech in the bad old days, magnets could be really bad news. They were fine on the fridge, no problem at all. Put one near a floppy disk, or a hard drive, or even a computer monitor, though, and you were in for some pain. You’d lose data, possibly permanently destroy a disk or drive, or you’d get ugly smeary rainbow effects all over your screen.

The solid state revolution has eliminated a lot of these problems. We all use SSDs, flash drives, and LCD monitors now, all of which care a lot less about flirting with magnets. However, the same can’t be said about all our modern hardware, for a magnet could cause your smartphone some major grief indeed.

Magnetic Fields

As you might expect, the magnetic susceptibility of certain modern smartphones once again comes down to non-solid state parts. Now, there aren’t exactly a lot of phones out there that are packing hard drives or floppy drives or any sort of magnetic storage. Instead, it all comes down to cameras.

Take the modern iPhone line, for example. Apple is quite careful to warn against carelessly using magnetic accessories with the smartphone, because it can interfere with the cameras. Specifically, it’s because of the optical image stabilization (OIS) and closed-loop autofocus systems that are built into the cameras themselves. These devices use magnetic position sensors to determine lens position to compensate for focus, vibration, and movement, and use magnetic voice coil actuators to move optical elements, in order to take the best possible photos and videos at all times. If there’s a strong magnetic field in the vicinity of the lenses, it can interfere with this operation.

Few of us are sticking fridge magnets on our iPhones, to be sure. However, there are a lot of magnetic cases and mounts and other accessories that give people a great reason to stick magnets on their phone. In the cases of some third-party accessories that are poorly designed, it’s possible for these to cause problems with the camera if the magnets are too strong or too close to the key hardware. It’s worth noting that in typical use, something like a magnetic case or other small magnet won’t cause a lot of permanent harm. It will generally just degrade the operation of the camera until the magnet is removed.

This isn’t solely an iPhone problem, either. It can affect any phone that has any sort of magnetic sensing or actuation involved in the camera mechanism. Indeed, Samsung has even filed a patent on ways to mitigate this problem through carefully orientating the magnets used in folding phone mechanisms, and the appropriate use of shielding. Ultimately, similar camera technology is used in a great many phones, all of which are susceptible to this problem.

It’s true that in day to day use, you’re probably not going to run into a lot of problems waving around a magnet near your smartphone. Nor did floppy disks fail en masse in the 90’s, unless one of your colleagues was feeling vindictive and wiped them all with a fridge magnet on their lunch break. Still, like the oddball helium problem that because apparent with smartphones a few years ago, it’s funny to think that magnets could be causing trouble with computer hardware today. The fact is that a modern smartphone contains multitudes, and thus can surprise you with its edge case frailties.