Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics:
Magnetic Field Due to a Current Element: Biot-Savart’s Law:
Biot-Savart’s law is an experimental law predicted by Biot and Savart. This law deals with the magnetic field induction at a point due to a small current element.
Note: Since, only dl have no direction, So we consider idl(current element) in the direction of current.