Since the distance between the Zeeman sub-levels is a function of the magnetic field, this effect can be used to measure the magnetic field, e.g. that of the Sun and other stars or in laboratory plasmas.
Charley horse: Slang for a cramp in a muscle in the leg, usually caused by a strain or injury. A charley horse can last anywhere from a few seconds to over a quarter of an hour. It is not uncommon for one to recur before it finally resolves.
Charley horse is another name for a muscle spasm. Charley horses can occur in virtually any muscle, but they are most common in the legs.These spasms are marked by extremely uncomfortable muscle contractions. The muscles donât relax for several seconds or more, and the pain can be quite severe.he most common causes of charley horses include: 1  inadequate blood flow to the muscle. 2  muscle injuries. 3  exercising in excessive heat or cold. 4  overuse of a specific muscle during exercise.