WEBVTT

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[unclear opening audio]

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Needle-nose pliers?

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Needle-nose pliers.

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Jumper wire.

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Jumper wire.

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Capacitor.

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Um, which one is the capacitor again?

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Oh, it's the blue round thing on the left.

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Aha!

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One capacitor.

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For you.

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Thanks, Adabot.

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Ladyada, what does a capacitor do?

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A capacitor stores electrical energy.

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But isn't that what a battery does?

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Well, yes, both a battery and a capacitor store electrical energy.

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But other than that, they're quite different.

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Oh, but what makes them different?

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Well, a battery generates electrical energy using chemistry,

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whereas a capacitor has to be charged from an external source

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before it can supply electrical energy.

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So a battery makes electricity, but a capacitor stores it.

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That's right.

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Can a capacitor be filled with electricity from a battery?

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Absolutely.

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Cool, but why would you want to do that?

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That's a good question. You might want to ask a capacitor.

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Good idea. I'll go ask Cappy.

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Hello, Cappy. How are you doing?

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Oh, hello there, Adabot. I'm doing quite fine. Yourself?

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All systems are fully operational, but I have a question. What do you do in this

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circuit?

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Oh, good question. In this circuit, I'm filtering power.

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Oh, how do you do that?

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Ah, well you see, this circuit is a power supply.

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We take electrical power in on one side, fix it up, smooth it out, and we send it

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out the other side.

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And I'm the part who does the smoothing.

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When too much electricity is coming in, I store the extra.

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And when too little electricity is coming in, I empty out my stored electricity to

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fill in the gaps.

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Wow, I guess you're a pretty powerful guy around here.

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You might say that, kiddo, you might.

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But capacitors do more than just filter power.

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Really? What else do they do?

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Ah, let's see.

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Capacitors store lots of power to help keep photos brightly lit.

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A camera flash?

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Precisely.

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When the power goes out, capacitors can help a computer run for a bit.

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Backup power?

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Right again.

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A capacitor can let low notes play while filtering out the higher ranges.

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That's an audio filter.

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Correct. Capacitors can block electron flow while passing along electrical changes.

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Uh, I don't know that one.

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Oh, that is kind of a tough one. It's called AC Coupling. Don't worry about it.

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Okay.

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There's just one more thing you should know. Some capacitors can dance.

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What?

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Capacitors do a lot of important work inside of circuits by storing and releasing

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electrical energy.

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Agreed. But where do you store all that energy? Some kind of backpack or big pocket?

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No, I store electrical energy right here in my body.

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Whoa!

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Inside every capacitor there are two electrically conductive plates,

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separated by a layer of material that doesn't conduct electricity.

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electricity. Electrical energy is stored in a capacitor when many

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electrons gather on

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one plate, all trying to reach the other plate which has more empty spaces for the

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electrons

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to fill. Oh, just like in a battery, the electrons crowd up on one

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side, hoping they can fill

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the empty spaces. Indeed. And, a capacitor releases electrical

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energy when those electrons

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find an easier way to get to those open spaces by going outside

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of the capacitor's body.

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Thanks, capacitors make a lot more sense now.

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You're very welcome Adabot, glad I could help. Oh that reminds me,

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I should get back to work at that power supply circuit.

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Right, see you later Cappy.

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Oh, hey, welcome back, Adabot. So, did Cappy tell you all about capacitors?

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He did. He's a pretty amazing guy. Capacitors can be used in all sorts of

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different ways.

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That's right. They also come in many different sizes and colors, like these.

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Wow, those are all capacitors?

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That's right. Different types of capacitors for different types of jobs.

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from teeny disks to ceramics, film, and electrolytic capacitors.

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We even have huge super caps.

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Let's try and experiment with this capacitor.

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This fellow has 10,000 microfarads of capacitance and can be used up to 6.3 volts.

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I'm going to measure the voltage on this empty capacitor with my multimeter.

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Right now we're at zero volts.

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Now I'm going to charge my capacitor with these two AA batteries.

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All I have to do is touch the leads to the capacitor to charge it up to 2.5 volts.

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Now we can use the stored energy inside this capacitor to light up an LED.

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Ladyada, there's still one thing I'd like to know.

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What's that, Adabot?

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Well, why don't your capacitors dance?

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What?

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You know, do-da-do-da-do-do-do-do-dee-do.

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Do-da-do-da-do-do-do-do-do-do-do-da.

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