 So now we're going to take a look at finding the equivalent capacitance in a series set of capacitors. And this is a little bit more complicated than the capacitors in parallel, so we're going to handle it in two different videos. So again, finding the equivalent capacitance, if not the whole problem is often the first step of a problem. And so we need to take a look at what that equation is. Well, the equation for a series set of capacitors is the inverse equation. So 1 over the equivalent capacitance is equal to 1 over C1 plus 1 over C2. Now that gives me 1 over the equivalent capacitance. If I want to actually go through here and find the equivalent capacitance, I would have to take 1 over that quantity, 1 over C1 plus 1 over C2. Let's go ahead and look at an example calculation to make sure you understand how to work with that. So let's have a 2-farad capacitor and a 3-farad capacitor. When I plug that into the equation, or as it's probably going to look when you plug it into your calculator, 1 over 1 over 2 plus 1 over 3. And that gives me a value of 1.2 farads. And this points out something important, which is in series when you compare or add up these capacitors in series, the equivalent capacitance will always be less than the original values. So my 1.2 is less than either 2 or 3. Because it was originally 2 farads and 3 farads that I was comparing this to. Because this equation is a little bit more complicated, I often see several different common student mistakes. The first common mistake I see is when students try and do this in two parts. And the first thing that they do is they do the 1 over 2 plus 1 over 3. And they get a value of 0.833. And they look at it and say, okay, yes, that's a smaller value than 2 or 3. That's my final answer. But they haven't. They've only done this side of the equation. There's still 1 over that value. So what happens is in order to get the correct answer, you would have to do one more step, which is 1 over 0.833. In order to give you the correct value of 1.2. The other common error I see is that when students put this in, they put their parentheses in the wrong place. So they're trying to type this in, but what they end up typing in is this. And it's a subtle issue here. So we're trying to see what exactly it is that they've done, which is not the right thing. And the trick here is that what the calculator is actually seeing is 1 over 1 over 2 plus 1 over 3. And it's not keeping that 1 over 3 on the bottom of the equation. And so they get the wrong answer there. If you want to use parentheses and make sure that you're putting them all in the correct spots, what you really need to do is have an outside set of parentheses holding the entire denominator together. And then perhaps a 1 over 2 in parentheses and a 1 over 3 in parentheses. But don't forget the outside parentheses so that the entire denominator is kept on the bottom of the equation. Once you get used to working with these, you'll get a little bit more used to it. But you do need to practice this to make sure you're putting things into your calculator correctly and not getting one of these types of wrong answers.