What is a "Volt" in Electricity?
The Volt is a unit of measurement for how much force we have making electrons move toward one direction compared to how many electrons we have. It's abbreviated V. It should be capitalized because it comes from the name of the scientist Alessandro Volta1. The property is called voltage.
Technical Definition
The Volt is standard unit defined as 1 Joule per 1 Coulomb, or 1 Watt per 1 Ampere2.
The Joule is a measurement of force or energy. For example, 1 Watt is 1 Joule per second3.
The Coulomb measures an amount of electricity defined as:
Coulomb (unit of quantity of electricity) - The coulomb is the quantity of electricity carried in 1 second by a current of 1 ampere.
Resolution 2 of the 41st CIPM (1946) [https://www.bipm.org/en/committees/ci/cipm/41-1946/resolution-2] (accessed 2025-02-23)
The Ampere is in turn (currently) defined as:
[...] one ampere is the electric current corresponding to the flow of 1/(1.602 176 634 x 10–19) elementary charges per second.
https://www.bipm.org/en/si-base-units/ampere (accessed 2025-02-23)
And finally an "elementary charge" is an estimation of how much charge a single electron or proton carries.
You could say electricity happens when electrons move from one point to another, or when charges move from one point to another. It means practically the same thing.
The Joule being an amount of energy, and the Coulomb being an amount of electrons, means that the volt is just how much energy we have considering how many electrons we have.
Volt (unit of potential difference and of electromotive force) - The volt is the potential difference between two points of a conducting wire carrying a constant current of 1 ampere, when the power dissipated between these points is equal to 1 watt.
Resolution 2 of the 41st CIPM (1946) [https://www.bipm.org/en/committees/ci/cipm/41-1946/resolution-2] (accessed 2025-02-23)
Observe that "1 Watt per 1 Ampere" means the same thing as "1 Joule per second per 1 Coulomb per second," so we can just remove the "per second" to get "1 Joule per 1 Coulomb."
Let's consider how voltage changes according to these units.
Let's say we have X volts.
If we increase the number of electrons, the voltage decreases, even though the amount of electrical energy stays the same. That's because electrical energy is measured in Joules, and we didn't change the Joules, we only changed the Coulombs, thus we retain the energy, and only change the voltage.
Similarly, if we decrease the number of electrons being affected by some force, the voltage will increase, but we still have the same amount of electrical energy.
Although this may sound strange, this is the concept behind a device called a transformer, which is used to increase or decrease the voltage of an electrical current. Naturally, we can't create energy out of thin air, so if voltage was electrical energy, such device would require extra energy to increase the voltage, or need to consume energy somehow to decrease the voltage. Neither of these things are required, as the amount of energy is retained despite voltage changes.
References
- https://www.nist.gov/pml/owm/si-units-electric-current (accessed 2025-02-23) ↩︎
- https://web.archive.org/web/20070618123613/http://www.bipm.org/en/si/si_brochure/chapter2/2-2/table3.html (accessed 2025-02-23) ↩︎
- https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.330-2019.pdf (accessed 2025-02-13) ↩︎