ELI5-Since compasses use the magnetism of the earth to point to north, how do the compasses on our phones do that?

Question

ELI5-Since compasses use the magnetism of the earth to point to north, how do the compasses on our phones do that?

In: Technology

Answer 1

The same way. They contain a sensor, that measures the magnetism of the earth and knows which direction is north.

Instead of a moving needle like a compass, these sensors use the so called Hall effect, where magnetism influences how electricity moves. That way you can build sensors which are just a few millimeter small, contain no moving parts and are much more sensitive than a classical compass.

These sensors can even measure the magnetic field in 3 directions, so you can find north, no matter how you direct your phone. A classical compass needs to be flat to the ground, to work properly.

With the right app you can also use this so called magnetometer sensor in your phone to measure the strength of magnets.