Dave Hewitt wrote:Not in themselves, but the electrics are when they're switched on, are they not? Certainly judging by the audible radio interference if a phone that's been left nearby gets an incoming call (a frequent problem with radio interviewees who are routinely asked by producers to turn off their phones before going on air), then I'd not want a "live" one anywhere near my compass. PS - My phone cover uses velcro!
The EM radiation given off by a phone call is nothing to do with it. If you are worried about your compass being exposed to electromagnetic radiation then keep it away from bright sunlight.
But...
I got my compass out and stuck it next to my Galaxy S8. Turned on, but screen off. Case (with magnetic clasp) removed.
Turns out it
does deflect my compass. I am not sure if this is because the phone itself has had bits of its casing magnetised by the clasp over time, or whether the phone itself is doing it. Could be the wireless charging coils, I dunno.
Fact is I keep my phone in a case with a magnetic clasp and now I am going to keep my compass in the other pocket. Somewhat amusingly this is marked as the "phone" pocket, which is way too small to contain a modern smartphone.