I hear it many trillions pf electrons but what about protons? What makes a charge positive or negative, is it the way they occupy space time?
How many electrons or protons are in a charge. If I = Q/t what does that mean?
In: Engineering
Not an expert, but this might be one of the “which came first? chicken or the egg” questions. A charge is basically a property of a fundamental particle (this isn’t a great explanation) The charge value determines how strongly the particle interacts with the electromagnetic field. What is the electromagnetic field? It is a field which interacts with charged particles.
While there isn’t any particle (that we know of) that makes an electron, a proton is made out of quarks. (2 up 1 down) Each quark has it’s own charge number and the sum of the charges of the quarks in a proton is assigned (arbitrarily) a positive sign and a value of 1. The electron (which is an elementary particle – ie not made out of other particles) is assigned a negative value of 1.
All the measurable stuff is just calibrated off these numbers. A +1 or -1 charge will interact with this amount of energy etc. All the units we choose are fairly arbitrary (there is no “rule” in the universe that defines one Ampere or one Coulomb – these are human defined for measurement purposes.) So we end up with “so many +1 charges or -1 charges makes up a Coulomb” (6.24… x 10^18) and if 1 Coulomb’s amount of charge “flows” past a point in 1 second we call that 1 Ampere.
TLDR: As far as we know, charge is a fundamental property of matter. In modern physics, everything is defined from certain fundamental properties of these elementary particles – charge, spin and mass.
Here’s the secret you don’t learn in high school: **charge isn’t real** (true of a few other things like force as well). It’s a useful way to be able to do math, and therefore to predict stuff, where electrons and protons are concerned.
Nature, though, doesn’t care. Nature doesn’t have to do math – nature just *does*, and we try to watch and describe it. We noticed that some things move in unexpected ways (see: glass/silk), and people proposed a bunch of explanations as to why (“[electric fluid](https://en.wikipedia.org/wiki/Fluid_theory_of_electricity)”, etc); then, we narrowed it down through experiments to the idea of “charge” we have today. In other words, charge is a mathematical construct that lets us predict what nature is going to do next.
Charge is just a property of matter. Charge is measured a lot of ways, but it always is a multiple of the charge of 1 electron (or proton; they’re the same, but opposite), which is called the elementary charge, or e. So, a simple way to measure it is to say a proton has a charge of 1e and an electron has a charge of -1e.
An atom with more protons than electrons will be positively charged, and an atom with more electrons will be negatively charged. If they balance out, it results in a charge of 0e.
The names positive and negative were initially just assigned arbitrarily and we keep them out of convention (even though it might actually have made some later discoveries a little more intuitive if they had been reversed, since a lot of electricity stuff deals with the movement of electrons). There’s nothing about the charges that makes them inherently “positive” or “negative,” they just needed opposite names.
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