Tesla (T), named after the Croatian engineer Nikola Tesla (1856-1943), is the unit of magnetic flux density specified in the International System of Units( SI). In SI units, one tesla is equal to the deflection of a magnetic field vector required to produce a force of 1 newton with a charge of 1 coulomb at a rate of change of one meter per second.
Since the tesla is a relatively large unit, milli-tesla (mT) and micro-tesla (µT) are used in practice. There is a direct relationship between the tesla and the current flow. In the unit system one Tesla corresponds to 1 Vs/m2, in the cgs system(centimeter, gram, second) 1 Tesla corresponds to `10^4` Gauss or `10^-5` Gamma. The earth magnetic field has a magnetic flux density of about 50 µT. With light magnetic materials like magnetite (Fe3O4) magnetic fields with a strength of about 0.5 T are reached, with permanent magnets about 1.5 T to maximum 3 T are reached.