# Biot-Savart Law¶

The Biot-Savart Law derives the magnetic field **B** due to a current:

Here, is the *magnetic constant*,
is the infinitesimal length and direction of a section of infinitesimally
thin wire current
we are integrating over, I is the amount of current in that section,
and **r** is the displacement vector from the section of wire current to the point
where **B** is measured.
may also be replaced with if a current density **J**
occupies a volume element dV.

## SIMION Specific¶

SIMION 8.0.3 can compute magnetic fields from wire currents using the Biot-Savart law
using the *simionx.MField - Biot-Savart magetic field calculations* library. In SIMION 8.1.0.19, these wires can also
be drawn on the SIMION View screen. Examples of this include

- SIMION Example: solenoid (see also
*Solenoid Magentic Field*) - SIMION Example: helmholtz_coil (see also
*Helmholtz Coil*)

See also *Magnets* and Wikipedia:Biot-Savart_law.