 This video is going to be a walkthrough of capacitors in series in the circuit and we're going to discuss charge and we're going to discuss bolt drops across each Capacitor, so we've got these guys here now again. This is just going to be a walkthrough. It's not going to be an in-depth lesson I'm going to assume that you know this from other videos, but we're just going to go through the math part of it right now Now again with this circuit here There's a few formulas that we're going to have to go through so let's take a peek at what formulas are dealing with with this Determining bolt drops across each capacitor So the formula is that we're definitely going to be needing is this is a big one for us This is q is equal to c times v the q is your charge and that is measured in coulombs. The c is your capacitance measured in Varides and the v is your voltage So we're going to see we're going to transpose this guy to figure out what our voltage is in a bit here now It's also important that we determine what the total circuit Capacitances now this is a theoretical circuit, so we don't have any resistance, but our capacitance our capacitors in series We add them up reciprocally 1 over ct is equal to 1 over c1 plus 1 over c2 plus 1 over c3 dot dot dot As because as we have these guys in series It is like we're taking all three of them adding them together and Increasing the distance between the plates and if you increase the distance between the plates in a capacitor they've increased the Decrease the capacitance Then the last one is this we're taking this video because we're going to try to determine the voltage across each capacitor We're just going to take this guy and transpose it and it works out to be this voltage across the capacitors equal to the charge divided by the capacitance So let's take a peek at the walkthrough here In this case, I've got a hundred and forty volts Source I've got a 20 micro farad capacitor a 40 micro farad capacitor and a 50 micro farad capacitor here The first thing we have to do is we're going to have to work out what our capacitance total is in the circuit I'm going to have to go 1 over 20 plus 1 over 40 plus 1 over 50 gets me 1 over and they'll get me the answer Which in this case is not 10.9 micro farads So in this nice little green there so we got 10.9 micro farads total circuit capacitance We need to work out what our charge is now if you go back a couple seconds there to where I talked about the formulas Q is equal to C times V So all we have to do is take this voltage here a hundred and forty volts and we'd multiply it by ten point nine micro farads remember you have to convert that back to farad, so it's gonna be 10.9 times 10 to the negative 6 and we get the total charge in the circuit Which works out to be 2.5 milliculons Now if you remember in a circuit especially series not especially in a series circuit The one thing that doesn't change is the current the current remains constant if I had five amps total here I'd end up having five amps across that five amps across that and five amps across that Charge all charges is the number of electrons in the circuit When you think about what current is current is the flow of charge or flow of electrons So we think of charge as being the same thing the charge is the same the whole way through the circuit if I have a total charge of 1.5 milliculons that means that this capacitor will have a charge across it of 1.5 Milliculons this guy will have a charge across it of 1.5 milliculons and this guy will have a charge across it of 1.5 milliculons, so let's get those drawn in there Okay, we've got our charges now if you might notice I've got and I do this intentionally I put my charge above my capacitance in each and every one So this guy was 1.5 over the 20 micro farads this guy's 1.5 over the 40 micro farads This guy's 1.5 milli over the 50 micro farads I do that intentionally because if you remember back to when we were looking at the formulas when we were determining the voltage Let me just get my handy dandy pen out here our voltage formula is V is equal to Q Over C So what I've done here is I've taken my Q and I just put it over my C So it reminds me that all I have to do when it comes time to determine the voltages is take this number 1.5 milli and divided by 20 micro and get the voltage So let's take a look and see how that plays out with the next slide here There you go. I take 1.5 milliculons divided by 20 micro farads and I get 75 volts I go over here and I got 1.5 milliculons divided by 40 micro farads, and I get 37.5 volts and over here I've got 1.5 milliculons 50 micro farads equals 30 volts I am now dropping the mic like a boss because I'm done. I've worked out the total circuit capacitance I've worked out the total circuit charge I've worked out each individual charge and from that I determine what each individual Voltages and if you add this up 75 plus 37.5 plus 30 gets you really really close to 140 volts That is how you determine the volt drop across each capacitor in a series capacitor DC circuit