An astatic magnetometer works by using two magnetized needles that are placed perpendicular to each other. The needles are balanced in such a way that their magnetic fields cancel each other out, making them unaffected by the Earth's magnetic field. When an external magnetic field is introduced, it causes a slight displacement of the needles, which can then be measured and used to calculate the strength and direction of the magnetic field.
The main materials used to make an astatic magnetometer are two small, lightweight magnetized needles, a non-magnetic frame or support to hold the needles, and a sensitive measuring device such as a galvanometer. The needles are typically made of magnetized steel or alnico, and the frame can be made of non-magnetic materials like wood or plastic.
An astatic magnetometer is typically very accurate, with a sensitivity of about 0.01% of the Earth's magnetic field. This means it can detect even very small changes in magnetic fields. However, its accuracy can be affected by external factors such as temperature, vibration, and stray magnetic fields, so careful calibration and control of these factors is important for accurate measurements.
Astatic magnetometers have a wide range of applications, including in geophysics, navigation, and scientific research. They are commonly used to measure the Earth's magnetic field, study the magnetic properties of materials, and detect anomalies in the Earth's magnetic field that may indicate mineral deposits or other geological features. They are also used in compasses and other navigation instruments.
Unlike other types of magnetometers, which typically use a single magnetized needle, an astatic magnetometer uses two needles arranged in an astatic configuration. This allows it to be more sensitive and less affected by external magnetic fields. Additionally, astatic magnetometers are typically smaller and more portable, making them ideal for fieldwork and other applications where precise, accurate measurements are needed.