Hello dear PF-members! :shy: I'm looking for some appropriate formula which could be utilized to calculate the magnetic field density in a straight high voltage AC mere cable. If you're more into the details of why I may ask this - I'm working with the railway maintenance and got interested in how a high voltage cable relates in a physical perspective besides of what I already know - that it carries 16 kV of fatal power. Besides the magnetic field density, I'd like to know if the inductance can be calculated and if the formula differs especially much if it's DC instead of AC? Also how far out the magnetic field (inductance) stretches out from the cable? I know some math so understanding such thing wouldn't be awfully hard I hope .. What I know is this 16 000 V 50 Hz (The length of the cable could be considered to be of optional length since it's railway cables) I found this formula but it seems to only be for the magnetic field density (Tesla) B=μ*(NI/l) Thank you for your help!