'Tesla' Defined As a Unit of Measure
The tesla (symbol T) is the SI derived unit of magnetic field B (which is also known as "magnetic flux density" and "magnetic induction"). One tesla is equal to one weber per square meter, and it was defined in 1960 in honor of the Yugoslavian-American inventor, physicist, and electrical engineer Nikola Tesla. One billionth of a tesla is a nanotesla, equivalent to 0.01 milligauss (mG), and it is in nanoteslas that common metric home measurements are made to determine local magnetic field levels. The strongest fields encountered from permanent magnets are from halbach spheres which can be over 5T.
This SI unit is named after Nikola Tesla. As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is uppercase (T). When an SI unit is spelled out in English, it should always begin with a lowercase letter (tesla), except where any word would be capitalized, such as at the beginning of a sentence or in capitalized material such as a title.