I was told this idea works for any sign of the source charge: in any potential, a positive test charge will always naturally move towards a lower potential and a negative test charge towards a higher potential.
I can kind of understand why a positive charge would move towards the region of lower potential (because don’t things in general want to do that? but if the source charge doesn’t matter, I’m just confused).
Can someone explain like I’m stupid why a negative charge would move towards higher potential?
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A positive point charge moves towards lower potential. A negative point charge is the opposite of a positive charge, so it moves away from lower potential. The opposite of lower potential is higher potential, so a negative charge moves towards higher potential.
It’s not that things “want to move towards lower potential”, it’s that things want to move in a certain direction, and we define “potential” based on that direction. Electric charges move in two different directions, so we just had to choose one direction to call low and one to call high.
Things can have positive or negative electric charge, but the “high/low” phrasing brings to mind gravity, and things can only have positive mass (which you might think of as “gravitational charge”).
But you can think of something like a helium balloon, which is lighter than surrounding air, as kind-of-sort-of behaving like it has negative “gravitational charge,” and it rises, that is, moves towards higher gravitational potential.
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