Overview
The Biot-Savart law calculates the magnetic field from a current-carrying wire:

Where:

• B is the magnetic field,

• I is current,

• dl is the infinitesimal element of the current-carrying conductor, which is a vector pointing in the direction of current flow,

• r is distance from the point,

• r^{^} is the unit vector in the direction of r (from the wire segment to the point of interest).

Significance
Crucial in electromagnetism and designing inductors and solenoids.