The magnetic field $\left(d\overrightarrow{B}\right)$ due to a small element $\left(dl\right)$ at a distance $\left(\overrightarrow{r}\right)$ and element carrying current i is

The magnetic field $\left(d\overrightarrow{B}\right)$ due to a small element $\left(dl\right)$ at a distance $\left(\overrightarrow{r}\right)$ and element carrying current i is

$d\overrightarrow{B}=\frac{{\mu }_0}{4\pi }i\left(\frac{\overrightarrow{dl}\times \overrightarrow{r}}{r^3}\right)$

Where, ${\mu }_0$= permeability of free space