I was wondering if I could ask a question on the magnetic field surrounding a current-carrying wire, and how this field might change with the presence of other, ferrous materials nearby. I have been using this web page http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html#c3 to calculate the magnetic field around the wire, which the page shows moving in concentric circles. The site gives the formula B = (μ0*I)/(2*pi*r) Where I is the current in Amperes, and r is the distance from the wire in meters. This formula is for a wire surrounded by air, but I am wondering what might happen if some other objects were close to the wire (as close as r in the formula) I am interested in a situation where a high permeability object and a low permeability object are positioned equal distance from the wire. I am assuming the presence of the high permeability material would make the magnetic field around the wire stronger. Would the field would still flow in a concentric circle, or would the field be diverted in the direction of the high permeability material? If the goal was to exert a stronger force on the low permeability object, would the resulting magnetic field have a stronger effect on the low permeability object?