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.
1 Charley horses in the upper leg are mainly caused by activities like running or jumping. 2  Some of the spasms occur because of the irritation of the nerve that connects to a muscle. 3  The most common type of Charley horse, found in the calf region, is often the result of kicking while swimming. Low levels of minerals, such as sodium, magnesium or potassium, in the body can be one of the reasons for Charlie horses. 2  Deficiency of calcium in pregnant women can also be another reason for the onset of Charley horse. 3  Low level of liquids in the body, while exercising, might be a probable cause of Charley horse.