Anderson Video - Circuit Elements

Professor Anderson
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Okay, so let me just say a couple things about -- about Austin's question. There are a few circuit elements that are going to be key, one of course is the battery. Battery we write with a V and the way you write it in a circuit is a long line and a short line. There's of course the resistor R that you write with a sort of squiggly line like that. There is a capacitor C. A capacitor is two parallel lines. Okay, not a long line and short line, that's a battery, capacitor -- capacitors two long parallel lines and then the last thing is an inductor. We're gonna write an inductor with an L and it actually looks like a corkscrew. These are the four basic elements that you would have in a circuit and so if I was going to draw the circuit it might look like this. Resistor R, capacitor C, inductor L, all powered by some voltage V. Now we know what resistors do, right? Resistors resist the current. Okay. They resist current. Capacitors, C, we know what those do, they store charge. All right, you can power up a capacitor, you put a bunch of charge on it. What do inductors do? Inductors, turns out, they do something very special, they resist changes in current. Okay, resistors just resist current in general but inductors resist changes in current. It's hard to rapidly change the current through an inductor. There's another really cool way to think about this and we haven't got to magnetism yet but we will soon. When capacitors charge up they store electric field E. Right. A capacitor that has a positive plate and negative plate, there's an electric field in there. But inductors store B fields, which are magnetic fields. And it turns out that that means that they are resistive to changes in current as opposed to just being resistive to current. These are the three elements, we're gonna learn all about how they play into the circuit and what they respond to. For now we've only introduced the resistor but in the next couple chapters we're going to introduce the capacitor and the inductor, maybe you guys already looking at that and laugh. Okay, that enough Austin?
Okay, so let me just say a couple things about -- about Austin's question. There are a few circuit elements that are going to be key, one of course is the battery. Battery we write with a V and the way you write it in a circuit is a long line and a short line. There's of course the resistor R that you write with a sort of squiggly line like that. There is a capacitor C. A capacitor is two parallel lines. Okay, not a long line and short line, that's a battery, capacitor -- capacitors two long parallel lines and then the last thing is an inductor. We're gonna write an inductor with an L and it actually looks like a corkscrew. These are the four basic elements that you would have in a circuit and so if I was going to draw the circuit it might look like this. Resistor R, capacitor C, inductor L, all powered by some voltage V. Now we know what resistors do, right? Resistors resist the current. Okay. They resist current. Capacitors, C, we know what those do, they store charge. All right, you can power up a capacitor, you put a bunch of charge on it. What do inductors do? Inductors, turns out, they do something very special, they resist changes in current. Okay, resistors just resist current in general but inductors resist changes in current. It's hard to rapidly change the current through an inductor. There's another really cool way to think about this and we haven't got to magnetism yet but we will soon. When capacitors charge up they store electric field E. Right. A capacitor that has a positive plate and negative plate, there's an electric field in there. But inductors store B fields, which are magnetic fields. And it turns out that that means that they are resistive to changes in current as opposed to just being resistive to current. These are the three elements, we're gonna learn all about how they play into the circuit and what they respond to. For now we've only introduced the resistor but in the next couple chapters we're going to introduce the capacitor and the inductor, maybe you guys already looking at that and laugh. Okay, that enough Austin?