This is an accurate magnetic field detector, featuring a three-dimensional indicator
that shows the real direction of the field; it also displays a simple graph of the
Magnetic Field (its total magnitude) vs. Time (a 20s interval at 10
samples/second). Our app (portrait orientation, Android 5 or newer) will only work on the tablets and smartphones that have a magnetic sensor. You can use the magnetometer to measure and study the magnetic field
by different sources (to verify its proportionality with distance, for example),
as a detector for magnets and metals and as an indicator for Earth's geomagnetic field.