Howdy, So, I'm curious, is there a general relationship between current input into an electromagnetic and the magnetic field that it generates in space? The trivial example is wrapping a wire around a rod, then sending a current through it which causes a magnetic field. My set up is a simple circuit, where we have a power supply, resistor, and electromagnet. I want to solve maxwell equations, and I want to find the relationship between B and I, that is B(x,y,z,t,I). I have Jackson, so if someone could refer me to an area in his book which may explain this, or any other sources I would appreciate it.