Compass Calibration & Earth's Changing Magnetic Field
You might have noticed the sometimes the compass on Physics Toolbox apps require calibration (or any app that uses a compass, for that matter). Although we now include a special notice for users when we anticipate it needs to be calibrated with instructions on how to do so, few resources are available that explain exactly how this works. What this comes down to is the fact that most mobile devices use the three-dimensional magnetic field detector. Some other apps will use GPS
