The SI unit of magnetic flux density is the tesla, named after Nikola Tesla.
Magnetic flux density describes the strength and concentration of a magnetic field, and the tesla has the symbol T. One tesla is equal to one weber per square metre. Because the tesla is a large unit for many everyday fields, smaller units such as the millitesla and microtesla are common.
Nikola Tesla made major contributions to alternating-current power systems, motors, and high-frequency electrical technology. The unit was adopted internationally in the twentieth century to recognize his work.
The tesla is sometimes confused with the gauss, an older centimetre-gram-second unit. One tesla equals 10,000 gauss. Earth’s magnetic field is measured in tens of microteslas, while medical MRI systems commonly produce fields measured in teslas.