The magnetometer sensor in your tablet or smartphone also utilizes the modern solid state technology to create a miniature Hall-effect sensor that detects the Earth's magnetic field along three vertical axes X, Y and Z.

The Hall-effect sensor produces voltage which is proportional to the strength and polarity of the magnetic field along the axis each sensor is directed. The sensed voltage is converted to digital signal representing the magnetic field intensity. Other technologies used for magnetometer may include magneto resistive devices which change the measured resistance based on changes in the magnetic field.

The magnetometer is enclosed in a small electronic chip that often incorporate another sensor (typically a built in accelerometer) that help to correct the raw magnetic measurements using tilt information from the auxiliary sensor.

In addition to general rotational information, the magnetometer is crucial for detecting the relative orientation of your device relative to the Earth's magnetic north.