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We know that formula of electric potential is kq/r.So in case of positive charge q is positive so electric potential is high than negative charges. Am I right?.And also in case of battery,positive terminal has high potential than negative terminal,Or part of conductor connected with positive terminal of battery has high potential and part of conductor connected with negative terminal has low potential.WHY?

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Convention. We could have also defined the negative terminal to be "high potential." However, that convention has to be consistent. The positive terminal is at the high potential, and that potential causes positive charges to flow from high potential to low potential. If we had defined the convention in the other direction, then the negative terminal would be the high potential, and that potential would cause negative charges to flow from high potential to low potential.

As it turns out, in reality, the charges that flow are the negative ones. It would have been "better" to define electrons to have a positive charge and flip the terminals of the battery. Much confusion in semiconductor physics arises from the reality that electrons move from low potentials to high potentials instead of the other way around.

We can blame Ben Franklin for that. When he experimented with electricity, he needed to pick a convention. He had no way at the time of knowing which charge carrier was actually moving. He effectively flipped a coin. Sadly, he chose the less convenient convention. By the time we figured out that electrons are the charge carrier that moves, it was too late to undo all of the years of convention.

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  • $\begingroup$ So its just a convention that positive charges have high potential? $\endgroup$ – Shobhit Swami Mar 2 '17 at 3:38
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    $\begingroup$ Basically. It's also convention that the proton has a "positive charge" and an electron has a "negative charge." All that matters is that the equations, charges, and potentials were all consistent. Positive/proton/high potential is one of those consistent ways to write the equation. Its similar to how we can either say the force of gravity F=mg in the downward direction or we can say it's F=-mg in the upward direction, or we could even say F=mg in the downward direction, but defined g=-9.8m/s^2. It just happens to be annoying that we did it this way. $\endgroup$ – Cort Ammon Mar 2 '17 at 9:45
  • $\begingroup$ You'll find there are quite a large number of examples in science where we could have modeled things differently, but settled on one particular model because it was the most convenient. This just happens to be a case where we settled on an inconvenient model. $\endgroup$ – Cort Ammon Mar 2 '17 at 9:47

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