The energy transported by electrons that flow through a conducting wire in a DC circuit, is electric potential energy. The wire is attached to a battery pole, and therefore the wire acquires a surface charge which gives the wire an equipotential equal to the battery pole potential. The wire surface gets the same (monopole) voltage 'V' as the battery pole. When the wire forms a circuit (a load and a return wire to the other battery pole), then electrons flow through the wire, perpendicular to the gradient of the wire potential (the radial electric field), such that the electric energy represented by the moving electron (eV) does not change, but is transported only from battery pole to the load. An analogue is the gravitational potential of a mass M at a height 'h' with respect to the Earth surface; the mass moves parallel to the Earth surface from A to B without changing its height: the gravitational potential energy E = M.h.g is transported from A to B. For example, a 9Volt battery has two poles with monopole voltages -4.5V and +4.5V with respect to infinity. If the circuit attached to the battery carries an electric current of 0.5 Ampere, then both wires transport 2.25 Watt from battery to the load, and the load dissipates 4.5 Watt. What happens if one of the battery poles is connected to ground (which is a zero Volt monopole)? Without knowledge about the dynamic properties of surface charge on electric circuits/electronics, one cannot truly understand the physics of Electrical Engineering applications, so it is very strange nothing is taught about surface charge dynamics in EE education. How fast flows surface charge with respect to the drift current in the bulk of conductors (or semi-conductors)?
