Magnetometer
A magnetometer is a specialized device designed to measure the strength and direction of magnetic fields. It serves various applications, from scientific research to everyday technology. Common uses include detecting buried metal objects in archaeological sites, aiding in navigation like compasses, and assisting in space exploration by studying celestial bodies' magnetic fields. The concept of magnetometers dates back to the early 19th century, with foundational contributions from scientists like Carl Friedrich Gauss and Nikola Tesla, who explored and expanded upon magnetic theories.
These devices can utilize fixed magnets or electromagnets, with the latter offering adjustable magnetic properties through electricity. Magnetometers are integrated into modern technology, including smartphones and tablets, where they help determine orientation and location. In various fields, magnetometers aid scientists in mapping Earth's geological features, predicting solar activity, and conducting medical research by tracking particles in controlled environments. Overall, magnetometers play a crucial role in enhancing our understanding of the physical world and improving everyday technology.
Magnetometer
A magnetometer is a device capable of measuring both the strength and direction of magnetic fields. Magnetometers have many purposes and designs, including detecting and measuring areas of magnetism, finding objects made of metal, and helping to determine the direction and position of objects relative to a magnetic field. A compass is a simple magnetometer designed to detect true north by the strength and direction of its magnetic field. Other magnetometers can be designed to perform specific functions based on how they measure and detect the direction of sources of magnetism. Magnetometers are so useful that they have become part of everyday life, even if users are sometimes unaware of their presence.
Background
The first magnetometer was made by German scientist and mathematician Carl Friedrich Gauss in 1832. Using a straight bar-shaped magnet suspended by a thread made of gold, Gauss hung the bar horizontally and devised ways to use its dipolar, or two-pole, properties to test the location and strength of a magnetic field. Gauss established a laboratory for studying the properties of magnetism where, among other things, he helped to develop a magnetic telegraph, established a network of observatories to study Earth's magnetic fields, and developed several key theories related to magnetics. The strength of a magnetic field is sometimes measured in units called "gausses" in his honor.
Others built on Gauss's work and incorporated magnets and magnetic fields into a number of new mechanical devices. Serbian-American inventor Nikola Tesla was among those who used and built upon Gauss's theories. Tesla discovered rotating magnetic fields and created several devices that incorporated magnets and used magnetometers in their design. Another unit of magnetic measure, equal to ten gausses, is named after Tesla.
Since these earliest experimenters worked with magnetometers, several designs have been developed to serve various purposes. Some used fixed magnets, much like those used by Gauss in the first magnetometer, while others use electromagnets. An electromagnet is a bar of metal wrapped with a metal coil that receives its magnetic charge through electricity. Electromagnets offer advantages over fixed magnets in that the charge can be increased or decreased based on the amount of electricity used. No matter what type of magnet it uses, however, a magnetometer works by using disturbances in its magnetic field to measure the strength of another source of magnetism and its direction relative to the magnetometer.
Overview
The ability to detect and measure the strength of magnetic fields makes magnetometers useful in a number of ways. Since Earth and many other celestial bodies have magnetic fields, scientists have been able to uses magnetometers to learn more about them. Magnetometers have been integrated into devices that gather information; find objects that are hidden by sea, land, or space; and even help common everyday objects to function.
Magnetometers are used to study the magnetic field of Earth. Magnetometers have allowed scientists to discover the metals that make up Earth and learn about changes in the magnetic field that have occurred over thousands of years. One way they do this is by studying how the iron in fossils has realigned itself over time in response to changes in the magnetic field and comparing these changes to more recent readings taken with magnetometers. Magnetometers can help to map and survey Earth, especially with relation to deposits of metal.
Magnetometers can be used to study objects in space by testing and recording changes in these objects' magnetic fields. The National Aeronautics and Space Administration (NASA) has launched a number of missions that have included magnetometers, including some designed to measure changes in the Sun's magnetic field that can predict solar flares before they occur. Another mission, called the Mars Atmosphere and Volatile Evolution (MAVEN) mission, launched in 2013 to test the magnetic field of Mars and determine how that field impacts Martian climate. NASA planned to launch a magnetometer to measure the magnetic field of asteroid Psyche in 2023.
Archaeologists frequently use magnetometers to find sites to explore by looking for buried metal objects. Professional archaeologists have specially designed and highly sensitive portable magnetometers, while hobbyists often use a more common version of a magnetometer in the form of a metal detector. Metal detectors work by deploying magnetometers to measure changes in Earth's magnetic field caused by metal objects that are between the field and the metal detector. Similar technology is used when hunting for ships or planes lost at sea. A boat dragging a device with a magnetometer inside can search for sources of metal, such as a ship's anchor, anchor chain, or hull or parts of an airplane that are submerged underwater.
One of the most common uses for magnetometers in the twenty-first century is in portable electronic devices. Metal detectors used by police and airport security use magnetometers to detect weapons. Cell phones, tablets, and gaming controls often contain a number of tiny sensors and devices such as magnetometers that work together to enable them to provide sophisticated functions. Unlike the larger units in metal detectors, search ships, or scientific laboratories, the magnetometers in electronic devices are very small. A phone, for instance, often has three magnetometers that detect magnetic fields and help to determine the device's position relative to these fields. This information, combined with global positioning satellite (GPS) technology and devices such as accelerometers and gyroscopes, can help determine the phone's position relative to true north and make tracking the phone's geographic location possible. As a result, the user can determine his or her location on a map and follow along in real-time as he or she moves with the phone.
Magnetometers have had an influence in medical research, too. For instance, a study conducted at Massachusetts Institute of Technology in the 1970s determined that smoking impairs the lung's ability to clear inhaled debris. The study used a specially prepared room that eliminated virtually all magnetic fields as a test site and used a magnetometer to detect and track small harmless iron oxide particles that were intentionally inhaled by study participants. The magnetometer testing showed that while the lungs of non-smokers were able to clear all but 10 percent of the metal particles within a year, the smokers' lungs were able to remove only about 50 percent of the particles.
Bibliography
"How Do Smartphones Work Out What Direction They Are Pointing?" British Geological Survey, www.geomag.bgs.ac.uk/education/smartphones.html. Accessed 27 Dec. 2016.
"Magnetometer." East Carolina University, www.ecu.edu/ncshipwreck/magnetometer.htm. Accessed 27 Dec. 2016.
"Magnetometer Data and Determining Today's Magnetic Storminess Using a Single Number." University of California at Berkeley, cse.ssl.berkeley.edu/segway/WSW‗kindex.html. Accessed 27 Dec. 2016.
"Magnetometer: The History." CT Systems, www.ctsystems.eu/support/magnetometer-the-history/. Accessed 27 Dec. 2016.
"Magnetometers, X-Rays, and More: Airport Security Technology." FOX News, 29 Dec. 2009, www.foxnews.com/tech/2009/12/29/magnetometers-x-rays-airport-security-technology.html. Accessed 27 Dec. 2016.
"Measuring Mars: The MAVEN Magnetometer." National Aeronautics and Space Administration, 26 Mar. 2013, www.nasa.gov/mission‗pages/maven/news/magnetometer.html. Accessed 27 Dec. 2016.
Stern, David P. "About Electronic Magnetometers and About Smoking." Goddard Space Flight Center, National Aeronautics and Space Administration, 12 Apr. 2007, pwg.gsfc.nasa.gov/earthmag/magmeter.htm. Accessed 27 Dec. 2016.
Stern, David P. "Gauss and the Global Magnetic Field." Goddard Space Flight Center, National Aeronautics and Space Administration, 23 Feb. 2008, pwg.gsfc.nasa.gov/earthmag/gauss.htm. Accessed 27 Dec. 2016.
Zuber, Maria T., et al. "The Psyche Gravity Investigation." Space Science Reviews, vol. 218, 18 Oct. 2022, DOI: 10.1007/s11214-022-00905-3. Accessed 19 Jan. 2023.