Problem: Only a single wire is necessary to make a phone connection. Consider that both terminals have some metallic objects grounded, making the Earth the other wire. Assume these objects are spheres of radius r deep in the ground. The distance between the terminals is L.
1. What is the resistance (due to the earth) between the terminals? Assume that the resistivity of the earth is uniform, and L>>r.
I want you to clarify the physics in this above problem.