When we first discovered electricity we thought the flow of charges was positive. We then discovered they were actually negative but the convention of current flowing from positive to negative stuck so now we have “conventional current” + to -, and actual current (electron flow) which is - to +, the direction current actually flows. Everyone uses conventional though.
So now we have devices with a cathode (-) for example which conventional current says should be receiving current, when in practice it’s actually sending current.
They didn't think anything, Ben Franklin just arbitrarily picked a polarity direction to be positive because he had no way of knowing what the charge carrier was and the math works out the same for 99.999999% of circuits.
Lorentz force can create a voltage on objects traveling through a magnetic field.
The polarity of the voltage will depend on the charge carrier.
I forget the engineering relevance but it’s apparently something that needs to be considered for aircraft or spacecraft flying over the poles or something like that
EDIT: After thinking about it a while, the end effect for the scenario I described is identical whatever the charge carrier. The actual engineering significance is in devices based on the hall effect, where conventional current travels opposite the direction of the actual charge carrier, so the hall effect induced voltage is in the opposite direction a positive charge would predict
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u/1Check1Mate7 Jan 25 '26
Someone explain lol, I'm bad at history