I remember when I was growing up (decades ago), my dad instilled in me to never put a magnet up to a computer or TV because they would cause irreparable damage to the screen. While I’m sure that SOMEWHERE out in the world there’s a magnet strong enough to cause damage if given enough time or whatever, but in terms of what I can buy from a store, would it be safe to keep my cell phone and a magnet (say, one of those ‘clicking’ fidget toys with half a dozen or so small magnets) in the same pocket, or am I just asking for trouble?
Edit: Thank you everyone for all your answers! I now know far more than I expected to from this silly question 😁
And, really, when it comes to general electronics that aren’t CRT screens or hard drives, it’s not the strength of the magnet that ultimately matters – it’s how quickly and how intensely the magnetic field changes.
Changes in magnetic field will induce currents in any nearby conductive material, including the circuit board traces and wires of any electronic device. If a strong enough magnetic field changes fast enough, the induced currents will be higher than the components can handle and damage the device. Small, weak magnets are unlikely to ever be a problem, since you’d have to get them moving very fast in order to reach that damage threshold. But, on the other side of the magnetic power spectrum, even extremely strong magnets won’t cause damage as long as they’re moved slowly relative to the device. The more powerful the magnet, the slower you need to be in order to avoid damage.