# Magetic field due to straight current wire

1. Jan 9, 2008

### el_greco

1. The problem statement, all variables and given/known data

We have a system of cylindrical coordinates (r,φ,z) and a straight electrical current wire along the z axis. The objective is to create a matlab plot of the magnetic field due to this current wire.

2. Relevant equations

Ampere's law gives us that B=m0*I/2πr for that current wire, for any given r (perp distance from the z axis).

3. The attempt at a solution

As a vector, this is Bφ, since the right hand grip rule tells us that the magnetic field lines follow the four right hand fingers at the φ direction, when the thumb shows the electrical current. So now I just want to plot this Bφ for a few r lines, for φ=0 to 2π, ie to obtain a few circles around this wire... Any idea how? :S