2 ms·

Ah, service tech makes sense. Most others aren't going see anything interesting in the photo that close. Laptop is pretty crazy, what where they (not) thinkin

by ska 5y ago

Ah, service tech makes sense. Most others aren't going see anything interesting in the photo that close. Laptop is pretty crazy, what where they (not) thinking? I guess was imagining "normal" camera not phone, but you are right that modern attempts to make phones light have removed most of the magnetic material. It doesn't take much to make it a problem (e.g. steel screws). Typical rooms are going to over 20g acceleration on ferromagnetic components in the highest gradient regions.

lostlogin 5y ago
Absolutely. The engineer with the laptop had a brain fade - his area was usually CT. As magnets have got better control over their fringe fields, the issue has got worse. The field goes from nothing to 3T in a very short distance, so 10+ T/m rate of change is not uncommon.
- pvaldes 5y ago
  Not everybody has access to Computer Tomography machines but lets examine a more common situation. Moving our magnet to the fishing area. Lets imagine that we put, not a magnetic string, a standard size neodymium magnet for fishing in the front seat of our car... or we move it in the car trunk (but forgot that our car has the battery located inside the trunk (as several BMW or VOLVO models do, for example). What could happen?
  - ska 5y ago
    There are basically two purely EM mechanisms at work for large static fields. First, if the field is big enough, it will saturate components that rely on EM effect to work - these will stop functioning until they are removed from the field. Permanent damage possible if other components behave badly in this situation. The other thing is if you move in the field you will induce currents on anything like a conductive loop in your device. Damage potential is really dependent on the strength, speed of motion, and how sensitive your device is. Of course, if you have magnetic materials, mechanical damage is also possible. I suspect those fishing magnets fall off fast enough you'd have to get it lined up just right to a control board to see any effect, if then.

by ska 5y ago

lostlogin 5y ago

Absolutely. The engineer with the laptop had a brain fade - his area was usually CT. As magnets have got better control over their fringe fields, the issue has got worse. The field goes from nothing to 3T in a very short distance, so 10+ T/m rate of change is not uncommon.

pvaldes 5y ago
Not everybody has access to Computer Tomography machines but lets examine a more common situation. Moving our magnet to the fishing area. Lets imagine that we put, not a magnetic string, a standard size neodymium magnet for fishing in the front seat of our car... or we move it in the car trunk (but forgot that our car has the battery located inside the trunk (as several BMW or VOLVO models do, for example). What could happen?
- ska 5y ago
  There are basically two purely EM mechanisms at work for large static fields. First, if the field is big enough, it will saturate components that rely on EM effect to work - these will stop functioning until they are removed from the field. Permanent damage possible if other components behave badly in this situation. The other thing is if you move in the field you will induce currents on anything like a conductive loop in your device. Damage potential is really dependent on the strength, speed of motion, and how sensitive your device is. Of course, if you have magnetic materials, mechanical damage is also possible. I suspect those fishing magnets fall off fast enough you'd have to get it lined up just right to a control board to see any effect, if then.