Generation and Measurement of Magnetic Fields

In basic science areas, such as semiconductor physics, superconductivity, structural biology, and chemistry, magnetic fields are used as a powerful tool for analysis of matter because they can change the physical state of a system. In the presence of a magnetic field, the angular momenta (spins), the orbital motion of charged particles, and therefore the energy of the investigated physical system, are altered. One must realize, however, that the size of the induced effects are very modest compared to other physical quantities. The use of magnetic fields and their effects on matter are based on a few micro- and macroscopic principles. These principles are utilized not only in basic science areas but also for significant industrial applications, and most of them are also employed to measure magnetic fields. These include the following: Magnetization of nuclei and its decay; induced currents; force on moving charged particles(“Lorentz force”); magnetization; and energy content. Magnetic fields can be generated by magnets created from hard magnetic materials and by electromagnets. Permanent magnets offer a simple, fast, and cost-effective way to provide small-volume fields. Permanent magnets are being employed for MRI applications, accelerator storage rings, and wiggler magnets. Dimagnetism, antiferromagnetism, and ferromagnetism are explained. Keywords: magnetic fields; generation; permanent magnets; electromagnets; superconducting magnets; resistive magnets; pulse magnets; laboratory use; measurements; sensors