My professor decided to use the above reference directions when calculating power in circuits. He says that when power > 0, power is consumed. When p < 0, power is generated.
This definition is counter intuitive to what I would have assigned--I would have said negative means power is consumed and positive power means power is generated.
So my question is this: Are these sign conventions actually what is happening physically? In other words, when you look at the diagrams above, what determines (or what are the formal conditions based on the parameters above) that a system is generating or consuming power?
Do we understand it like this: On the left diagram, charge is flowing from "high" to "low" potential so charge is being used. And on the right, charge is flowing in its "opposite" direction so power is being generated?