I'm doing a simulation that involves measuring the permeability of space by measuring the magnetic field of a solenoid. I need to suggest and justify one reason why this would not work in the real world. I was hoping to talk about how the earth's magnetic field would have an effect but I'm confused about how to justify that, could I please have some help with that? For the second part of the question, I was going to suggest an experiment measuring the force between two wires but I'm also a unsure if that is applicable. Screenshot is provided for clarity

Question In reality, the above experiment (calculating up by measuring the magnetic field at certain positions from a single wire) is very impractical / difficult to accomplish with a high degree of accuracy in the real world. Suggest and justify at least ONE reason why this SPECIFIC experiment is difficult to conduct well in reality. You can use more than one reason if you like. Suggest and justify a DIFFERENT experiment you could use to measure up that would be better