It states that the magnetic field strength (dB) produced due to a current element (of current I and length dl) at a point having position vector relative to current element is
where µ0 is permeability of free space. Its value is
µ0 = 4π × 10CWb⁄A – m.
The magnitude of magnetic field is
where θ is the angle between current element and position vector .
The direction of magnetic field is perpendicular to the plane containing .