What does Kirchhoff's loop rule require of any closed circuit path?

1. Walking right round a loop returns you to the point you started from, at the same potential. 2. So the changes in potential met on the way must cancel, summing algebraically to zero. 3. Rearranged for a simple loop, this says the emf equals the sum of the IR drops in that loop. 4. Currents summing to zero is the junction rule, which applies at a point rather than around a path. _Source: OpenStax College Physics (CC BY 4.0), Ch 21 "Circuits and DC Instruments", section 21.3 Kirchhoff's Rules_