PHYS102: Introduction to Electromagnetism

Note that when people talk about junctions in circuits, they typically refer to the points where three or more wires come together. But in principle, even the connection between only two wires is a simple junction. It is just that we do not need any additional laws to figure out what the current and voltage on both sides of a two-wire junction must be: they are simply equal. You only face the difficulty of not being able to directly see what those quantities must be – without having to look to see how the junction is connected to the rest of the circuit – when you have junctions with more than two wires.

In Kirchhoff's second (loop) rule, we deal with voltages. Watch this video for a reminder that voltages are differences in electric potential.