Particular magnetic properties play an important role in detecting ferromagnetic objects in the ground. Magnetic field measurement makes use of the fact that foreign materials in the ground have a different effect on the Earth's magnetic field. These fluctuations in the Earth's magnetic field are measured by a magnetometer. This branch of science is also referred to as geomagnetics. Local deviations in the magnetic field on the Earth's surface indicate ferromagnetic materials in the ground. In this way, geomagnetics can be used to detect various objects such as contaminated sites (e.g., unexploded bombs) or archeological sites.