 Let's look at some of the basics for electric charges. If I've got an atom, it's made up of different components. You've seen this before, I'm sure. It's got protons and neutrons down in the nucleus where the protons are positive and the neutrons have zero charge or they're neutral. And surrounding that, we have our electrons, which are negative. If I'm going to symbolize it in physics for equations, I'm going to use a lowercase q as our main symbol for charge. Occasionally we'll have an uppercase q, particularly if the charge is spread out over an object. The units that we're measuring our q in are called coulombs, and we abbreviate that as a capital C. Coulomb's a scientist who did a lot of early work on charges. Now be careful not to confuse this capital C for coulombs with the Celsius degrees, which will generally have the small circle in it. You should be able to figure out from context which unit you're working with. If I look at individual charges, there's some relationships we see. Every electron, every single one of them has the same charge. And that's a charge of minus 1.602 times 10 to the minus 19th coulombs. Turns out every proton also has the same charge, but it's a positive 1.602 times 10 to the minus 19th coulombs. So this base amount here we're going to call the fundamental charge. And we give it a symbol of E, and it's 1.602 times 10 to the minus 19th coulombs, where we're not placing the negative or positive out front. Be careful that this E is not an electron. This E is not the E exponential button on your calculator. It's a new symbol. If we use this new symbol, then we can come back and express an electron as being minus E, and a proton as being plus E. If I've got a larger charged object, then the net charge on that object depends on the balance between the electrons and protons, not the total number of electrons and protons, just the balance between the two. The equation we use to represent this is Q is equal to a capital N times E. Q is our charge, N is the number of unbalanced charges, and E is our fundamental charge. So for example, if I have an object that's got the exact same amount of electrons and protons, then nothing is imbalanced, or N is zero, and it has no net charge. If I have an ion that has two extra electrons, well then that means I'm going to end up having a charge of minus 2E. It's negative because I have extra electrons, and there are two extra ones. Now an ion is just an atom where the electrons and protons aren't exactly the same number. So I might have 10 protons, but 12 electrons in this particular example. Now if I've got an ion with three missing electrons, then I would end up having a charge of plus 3E. Now again, we generally don't talk about having extra protons because it's not like we added protons to the atom. The nucleus is there in the center, and it stays pretty well protected. So if I had that same 10 protons in my nucleus missing three electrons, which means I only have seven electrons, so there's three missing, and that means I've got three protons that don't have matching electrons. If I want to look at a larger example, I can talk about what type and how many unbalanced particles does an object have and it has a net charge of minus 0.03 coulombs, just a little fraction of a coulomb. I start with my basic equation here, but now I want to rearrange it to solve for N, the number of unbalanced charges. When I plug my values in here for both my charge, net charge of my object, and the fundamental charge, what I find is that N is minus 1.87E to the 17th. Now what does that really mean? That means I have 187 quadrillion electrons. I know that they're electrons because it's negative, and so I've got a lot of extra electrons on this object, and yeah, quadrillion is a lot. Typical charges aren't going to be quite that much, even though 0.03 coulombs seemed like it was really small, a lot of real objects are going to have things in the range of microcoulombs. In a microcoulomb where micro is our metric prefix, is 1 millionth of a coulomb, or 1E to the minus sixth. Similarly, we'll often have nanocoulombs, where our nano prefix means E to the minus ninth, or 1 billionth of a coulomb. So you'll see these types of charges quite often, rather than full coulombs. So that wraps up our basic introduction to electric charges.