Spark image

Potential round a circuit

Diagram (a) shows that along the connecting wire from the cell to B there is no resistance and so no loss of electrical energy or drop in potential. In the resistors r and R energy is converted to heat and so the potential drops from B through to E. From E to the cell there is no loss of electrical energy and so the potential at E is the same as that at the negative terminal of the cell zero.

Diagrams (b) and (c) show that when no current flows in a circuit there is no change of potential and therefore no potential difference between two parts of that circuit that are connected while (d) shows an equal potential drop across parallel resistors.

(Assume that the energy lost in the connecting wires is negligible and ignore it.)

© Keith Gibbs 2011