energy
Kirchhoffs Second Rule Kirchhoffs second rule the loop rule is an application of conservation of energy. The loop rule is stated in terms of potential, V , rather than potential energy, but the two are related since PE elec = qV . Recall that emf is the potential difference of a source when no current is flowing. In a closed loop, whatever energy is supplied by emf must be transferred into other forms by devices in the loop, since there are no other ways in which energy can be transferred into or out of the circuit. Figure 21.23 illustrates the changes in potential in a simple series circuit loop. Kirchhoffs second rule requires emf equals the sum of the.