Magnetometer
Devices used to quantify the strength or direction of the magnetic signal of a sample are called magnetometers. There are very simple ones, such as the Gouy balance or the Evans balance, which measure the change in apparent weight that occurs in a sample when applying a magnetic field (due to the magnetic moment that is induced), and also very sophisticated, such as those endowed with SQUID, which are currently the most sensitive.
Magnetism varies from place to place, due to differences in the Earth's magnetic field (or Earth's magnetosphere), which can be caused by the different natures of rocks, and by the interaction between charged particles from the Sun and the magnetosphere of a planet. Magnetometers are a frequent instrumental component of spacecraft exploring planets.
Types
Magnetometers can be divided into two basic types:
- Scalar gauges measure the total strength of the magnetic field to which they are subjected. For example: procession magnetometers.
- Vector magnetometers they have the ability to measure the component of the magnetic field in a particular direction. For example: saturated core magnetometers (fluctuant).
A magnetograph is a special magnetometer that continuously records data.
Use on mobile devices
The magnetometer is used to turn the smartphone or tablet on or off, when a magnet approaches or moves away from it, in order to automatically turn the device screen on and off when its cover is opened or closed, without the need to press any button button.
On the other hand, most smartwatches, smartphones, and tablets have a built-in sensor that measures the Earth's magnetic field and can tell where north is, much like a compass (geomagnetometer).
In addition to this function, some applications can turn the magnetometer of a smart watch or mobile phone into a metal detector. They can make the magnetometer respond to metals such as nickel, iron, and steel, and could be useful for determining if there are wires behind a wall or even finding lost items behind a hard-to-reach place.