# Formula Biot-Savart law for thin conductors Magnetic field    Position vector to field point    Position vector    Electric current    Conductor line    Magnetic field constant ## Magnetic field

Unit
Magnetic flux density tells how strong the magnetic field is at the location $$\boldsymbol{r}$$ generated by a steady-state current $$I$$ through the conductor.

## Position vector to field point

Unit
Position vector from the coordinate origin to any point in space at which the magnetic field is to be calculated.

## Position vector

Unit
Location vector points from the coordinate origin to the infinitesimal conductor element $$\text{d}\boldsymbol{s}$$.

Here $$\boldsymbol{r} - \boldsymbol{R}$$ is the connection vector pointing from the infinitesimal conductor element $$\text{d}\boldsymbol{s}$$ to the field point. $$|\boldsymbol{r} - \boldsymbol{R}|$$ is the distance of the infinitesimal conductor element $$\text{d}\boldsymbol{s}$$ to the field point.

## Electric current

Unit
Constant electric current inside the conductor.

## Conductor line

The conductor through which the current flows.

Here $$\text{d}\boldsymbol{s}$$ is an infinitesimal length element. This length element runs along the conductor.

## Magnetic field constant

Unit
A natural constant with the value $$\mu_0 = 4\pi \cdot 10^{-7} \, \frac{ \text{N} }{ \text{A}^2 }$$.