My question is, are textbooks just saying the positive side of a battery has a higher voltage because mathematically + is higher than - even when, in reality, there is nothing to come out of the positive side?

The whole "convention" is really confusing me because "potential" semantically requires the one having potential being the one to exert power, when in reality, the positive terminal has no power to exert.

Or is my understanding a little off? Please help!

  • \$\begingroup\$ People like to use pressure for voltage and it may be a good start. Think of a garden hose with a certain water pressure; then of a fire hose with the same pressure. One can exert more power than the other, though, and given the same time to do it, do more work. So pressure isn't the same thing as power. A problem with this concept is that we really should be talking about potential differences between two points, not some idea of absolute "voltage" at a point. But save that for another day. \$\endgroup\$ – jonk Jul 25 '17 at 4:36
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    \$\begingroup\$ VTC - This question is not about electronics design as in the spirit of this xChange Stack. \$\endgroup\$ – Michael Karas Jul 25 '17 at 4:40
  • \$\begingroup\$ Positive side of what? \$\endgroup\$ – mkeith Jul 25 '17 at 5:09
  • \$\begingroup\$ Benjamin Franklin started this; respect the man. \$\endgroup\$ – analogsystemsrf Jul 25 '17 at 16:00
  • \$\begingroup\$ "there is nothing to come out of the positive side" is simply wrong. Read an intro about electrical current. \$\endgroup\$ – Dmitry Grigoryev Aug 3 '17 at 11:59

The potential of any point is a measure of the potential energy of a packet of charge at that point, relative to an arbitrary reference.

When a packet of charge moves from one point to another, it absorbs energy if going to a higher potential (charging a battery or a capacitor say), it releases energy if going to a lower potential (for instance heating a resistor).

Only differences of potential, that is voltage differences, are observable.

The conventions choose the size and polarity of the charge packet used to measure the energy. By convention, in electrical engineering, we use one coulomb of positive charge to convert between volts and Joules. We use positive charge regardless of the physical type of underlying charge carrier, whether it be holes in a semiconductor, electrons in a wire, ions in a plasma, protons in ice. Particle physicists use the charge on one proton to convert between volts and eV.

If we used a packet of negative charge to define the potentials, then our labels 'higher' and 'lower' would be reversed, however the world would still work just fine, as would all the mathematics as long as we applied the new convention consistently.

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