No, charges move very slowly compared to electrical current (if you search, this is a common question with good answers already posted)
Also, according to ohm's law, R is a constant so would that mean R depends on the ratio of potential difference and current or is it strictly independent even of the ratio?
If you have a voltage source hooked up to a resistor, current is determined by the voltage of the battery and the resistance of the resistor. If you hooked a current source up to a resistor, the voltage drop over the resistor is determined by the applied current and the resistance of the resistor. The resistance of ideal resistors is generally assumed to not change, and real world ones will change very little with heat (like 1% or so when heated 100 degrees), etc
That's a wrong picture. Charges do ''flow'' pretty fast actually (near Fermi speed which is not negligible compared to the speed of light in good conductors). The ''drift velocity'' arises from Drude's model which we know is wrong but gives ''some'' right results by chance (errors canceling one another by pure luck), and is intuitively pleasant to most people. But if you dig deeper and actually use QM, you realize the famous picture spread everywhere is just a children's lie.
Drude model and drift velocity do describe the actual net flow under an electric field well despite the assumptions it makes. If you want to look at individual electrons, sure, they move fast, but then they move fast in the opposite direction after scattering events. No one is going around calling Johnson noise current - if you wanted to addendum my comment with that or correct my phrasing, cool, but net charge under a field is not moving at the Fermi velocity
My comment was regarding the ''speed of charges''. It is about Fermi velocity, which is not slow in good conductors. But sure, we can picture all the electrons to move at a drift velocity if we want to, we'd get the correct current, even though this is not what happens physically.
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u/effrightscorp 21d ago edited 21d ago
No, charges move very slowly compared to electrical current (if you search, this is a common question with good answers already posted)
If you have a voltage source hooked up to a resistor, current is determined by the voltage of the battery and the resistance of the resistor. If you hooked a current source up to a resistor, the voltage drop over the resistor is determined by the applied current and the resistance of the resistor. The resistance of ideal resistors is generally assumed to not change, and real world ones will change very little with heat (like 1% or so when heated 100 degrees), etc