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by drostie 2852 days ago
It's ok, if I didn't have a Master's in the field I would probably have similarly down voted you.

The problem is mainly that the criticism you are making is not great for pedagogy. What is being called “charge” is probably something like “disposition to accumulate charge” or so, in the same way that force is not actually mass times acceleration, but it's mass times a disposition to accelerate, so that you can do things like measure my weight-force even though I’m not falling through the floor.

The dispositional truth of the matter is fundamentally more cognitively complex to teach than the simple rule that you get when you say that everything does what it's disposed to do, and so everybody has memorized the version of the definitions that has no dispositions, and gets very confused when you point out that aspect of those definitions.

2 comments

I suppose I also didn't provide an awful lot of explanation to my point, but I figured I could just explain when asked. I didn't expect the difference between current and a change in charge to be this controversial.
Except there has been no controversy at all. Everybody understands that current (i. e. flow of electric charge, water, etc.) may have nothing whatsoever to do with "change in charge" (or in the mass of water) contained in a volume of space through which charge or water flows.
If what's being called "charge" here is charge distribution between one side of the element and the other side within the circuit (basically, electrons to the left minus electrons to the right, divided by two lest we count a single moving electron twice), and what's being called "current" here is simply current across the element, then in this case, i = dq/dt.

That's a good mathematical model of the behavior of the elements from a pedagogical perspective, though confusing for more advanced readers.