What is the magnetic field at a distance of 2 m from an infinite current-carrying wire having current 4A?

The magnetic field produced by an endless wire may be calculated as follows:

$\mathrm{B}=\frac{{\mathrm{\mu }}_0\mathrm{I}}{2\mathrm{\pi R}}$

Where ${\mu }_0$ is the permeability of free space $=4\mathrm{\pi }\times {10}^{-7} \mathrm{N}/{\mathrm{A}}^2$, I is current, and R is the distance from the wire.

We have, 

Current, I = 4A

Distance, R = 2m

Magnetic field,  

$\begin{array}{rcl}\mathrm{B}& =& \frac{{\mathrm{\mu }}_0\mathrm{I}}{2\mathrm{\pi R}}\\ & =& \frac{4\mathrm{\pi }\times {10}^{-7}\times 4}{2\mathrm{\pi }\times 2}\\ & =& \mathbf{4}\mathbf{\times }{\mathbf{10}}^{\mathbf{-}\mathbf{7}}\mathbf{ }\mathbf{Tesla}\end{array}$.