The Electric Current

Abstract

Suppose that two separate points on a conductor such as a copper wire have a p.d. maintained between them; then an electric field will be set up inside the wire and it will act from the end at high potential V ₁ towards the end at lower potential V ₂ . In this case there can be no mechanism such as that of figure 3.2 to remove this internal field because the state of the conductor is dictated by an outside agency, namely the voltage source such as a battery, which maintains the p.d. (V₁−V₂) between the ends. Consequently all the free electrons, of charge − e will be acted on by a force F= Ee acting in an axial direction from right to left, as shown in figure 4.1a.