Kirchhoff's laws are valid for DC circuit and also for AC circuits (up to point. I think they become only approximations at high frequencies). Let's consider a node (junction) in a AC circuit. Three AC currents with the same magnitude but different relative phases enter the node. It is possible for zero current to exit the node, correct? It seems strange though that 3 currents enter and no current leaves the node. That cannot happen in DC: no charge accumulation can happen at any point in the circuit. But what does it physically mean that in the AC case the net current exiting the node is zero? That there is some charge accumulation and that the charge does not have an instantaneous velocity at that point? thanks!