# Biot-Savartâ€™s Law

Biot-Savartâ€™s law is used to determine the magnetic field at any point due to a current carrying conductor.

This law is although for infinitesimally small conductor yet it can be used for long conductors. In order to understand the Biot-Savartâ€™s law, we need to understand the term current-element.

According to Biot-Savartâ€™s law, magnetic field at point P due to the current element is given by the expression, also

In C.G.S., k = 1 and in S.I., . where Î¼0 = Absolute permeability of air or vacuum = 4Ï€ Ã— 10â€“7 Weber/Ampere-meter. Itâ€™s other units are;

Fig. 8

Vectorially,