c is for capacitor

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0:03[unclear opening audio]

0:30Needle-nose pliers?

0:32Needle-nose pliers.

0:34Jumper wire.

0:35Jumper wire.

0:37Capacitor.

0:38Um, which one is the capacitor again?

0:41Oh, it's the blue round thing on the left.

0:45Aha!

0:47One capacitor.

0:48For you.

0:49Thanks, Adabot.

0:51Ladyada, what does a capacitor do?

0:54A capacitor stores electrical energy.

0:57But isn't that what a battery does?

1:00Well, yes, both a battery and a capacitor store electrical energy.

1:04But other than that, they're quite different.

1:07Oh, but what makes them different?

1:09Well, a battery generates electrical energy using chemistry,

1:13whereas a capacitor has to be charged from an external source

1:17before it can supply electrical energy.

1:19So a battery makes electricity, but a capacitor stores it.

1:24That's right.

1:25Can a capacitor be filled with electricity from a battery?

1:29Absolutely.

1:30Cool, but why would you want to do that?

1:33That's a good question. You might want to ask a capacitor.

1:37Good idea. I'll go ask Cappy.

1:45Hello, Cappy. How are you doing?

1:48Oh, hello there, Adabot. I'm doing quite fine. Yourself?

1:51All systems are fully operational, but I have a question. What do you do in this

1:56circuit?

1:56Oh, good question. In this circuit, I'm filtering power.

2:01Oh, how do you do that?

2:03Ah, well you see, this circuit is a power supply.

2:06We take electrical power in on one side, fix it up, smooth it out, and we send it

2:11out the other side.

2:12And I'm the part who does the smoothing.

2:15When too much electricity is coming in, I store the extra.

2:19And when too little electricity is coming in, I empty out my stored electricity to

2:24fill in the gaps.

2:25Wow, I guess you're a pretty powerful guy around here.

2:29You might say that, kiddo, you might.

2:31But capacitors do more than just filter power.

2:34Really? What else do they do?

2:36Ah, let's see.

2:51Capacitors store lots of power to help keep photos brightly lit.

2:55A camera flash?

2:56Precisely.

2:57When the power goes out, capacitors can help a computer run for a bit.

3:02Backup power?

3:03Right again.

3:05A capacitor can let low notes play while filtering out the higher ranges.

3:10That's an audio filter.

3:11Correct. Capacitors can block electron flow while passing along electrical changes.

3:17Uh, I don't know that one.

3:19Oh, that is kind of a tough one. It's called AC Coupling. Don't worry about it.

3:25Okay.

3:26There's just one more thing you should know. Some capacitors can dance.

3:31What?

3:43Capacitors do a lot of important work inside of circuits by storing and releasing

3:47electrical energy.

3:50Agreed. But where do you store all that energy? Some kind of backpack or big pocket?

3:55No, I store electrical energy right here in my body.

3:59Whoa!

4:03Inside every capacitor there are two electrically conductive plates,

4:09separated by a layer of material that doesn't conduct electricity.

4:13electricity. Electrical energy is stored in a capacitor when many

4:19electrons gather on

4:20one plate, all trying to reach the other plate which has more empty spaces for the

4:26electrons

4:27to fill. Oh, just like in a battery, the electrons crowd up on one

4:32side, hoping they can fill

4:34the empty spaces. Indeed. And, a capacitor releases electrical

4:39energy when those electrons

4:41find an easier way to get to those open spaces by going outside

4:46of the capacitor's body.

4:51Thanks, capacitors make a lot more sense now.

4:54You're very welcome Adabot, glad I could help. Oh that reminds me,

4:59I should get back to work at that power supply circuit.

5:02Right, see you later Cappy.

5:08Oh, hey, welcome back, Adabot. So, did Cappy tell you all about capacitors?

5:12He did. He's a pretty amazing guy. Capacitors can be used in all sorts of

5:16different ways.

5:18That's right. They also come in many different sizes and colors, like these.

5:23Wow, those are all capacitors?

5:25That's right. Different types of capacitors for different types of jobs.

5:29from teeny disks to ceramics, film, and electrolytic capacitors.

5:34We even have huge super caps.

5:38Let's try and experiment with this capacitor.

5:42This fellow has 10,000 microfarads of capacitance and can be used up to 6.3 volts.

5:48I'm going to measure the voltage on this empty capacitor with my multimeter.

5:54Right now we're at zero volts.

5:57Now I'm going to charge my capacitor with these two AA batteries.

6:01All I have to do is touch the leads to the capacitor to charge it up to 2.5 volts.

6:09Now we can use the stored energy inside this capacitor to light up an LED.

6:17Ladyada, there's still one thing I'd like to know.

6:20What's that, Adabot?

6:21Well, why don't your capacitors dance?

6:23What?

6:24You know, do-da-do-da-do-do-do-do-dee-do.

6:28Do-da-do-da-do-do-do-do-do-do-do-da.

6:54[unclear audio]