I got really confused when all of a sudden they treated flux with the time domain equation notation. This is my first time seeing this. My question is simple, are there other quantities besides voltage and current that can be expressed as such in AC circuits? I just got curious would like to be exposed to the idea or not confined that only voltage and current exist in such a manner.
This is in the context of AC circuits because in general probably you could put any quantity in the y-axis and make a sinusoid and say it can. I want to see quantities that are related to AC circuits and may have some application.