b is for battery

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0:01[unclear opening audio]

0:43Hey, Adabot.

0:46Have you seen any of my batteries around?

0:48Oh, hi, Ladyada.

0:49I was just thinking about all the energy stored in these batteries, just waiting

0:53to be used.

0:54That's right. Batteries are really cool.

0:56And they're even cooler when they're used to power my multimeter.

1:04Batteries give us electricity on the go without needing to plug into a wall socket.

1:08But there's one thing I don't understand.

1:10What's that, Adabot?

1:12How do we fill batteries up with electricity in the first place?

1:16Well, batteries aren't really filled with electricity.

1:20They're filled with a bunch of components that generate electrical current.

1:24Oh, you mean they have little machines inside?

1:27Hmm, not exactly. I think we should look this one up.

1:31Agreed. Accessing database. Battery.

1:42There are two important parts of every battery, the positive and negative terminal.

1:55And if we opened up a battery, it would look like this.

2:01huh how does that make electricity well a battery uses chemistry to create electricity

2:07is called an electrochemical reaction oh sounds powerful

2:12it definitely is each terminal in a

2:16battery is made of a different kind of material the negative

2:22terminal is made of material that

2:23has a lot of extra electrons in it

2:25it looks

2:31pretty crowded in there it sure

2:33is and all those electrons really want to get some more space they want to go

2:37over to the positive terminal which has a lot of holes so the electrons can fit

2:41into them

2:41it doesn't look

2:47too far can't they just jump to the positive terminal

2:50they can't do that because the battery is filled with a special chemical

2:53called electrolyte, and it's very difficult for electrons to move through electrolyte.

3:04That's awful. If they can't move through the electrolyte, how are they going to

3:08get to those

3:09empty spots on the positive terminal? By traveling through a circuit. When

3:14connected to a circuit,

3:15the electrons can flow through the circuit from the negative to the positive terminal.

3:26They travel through all those parts just to get there?

3:29That's right.

3:30And they make all sorts of things happen along the way.

3:33You mean like lighting up an LED or making a motor move?

3:36Exactly.

3:37And it all starts inside the battery.

3:45Batteries are powerful.

3:47It must be pretty difficult to make them.

3:50Actually, we can make one right here.

3:52It's easy.

3:53Right, I'll go get the chemistry set.

3:55Wait, wait, don't go anywhere.

3:56Everything we need is right on this table.

3:59Oh, uh, a lemon?

4:05That's right.

4:05The juice inside of this lemon makes for a very good electrolyte.

4:09This galvanized nail is coated with zinc, and we can use that as our negative terminal.

4:14And this shiny copper penny will make a good positive terminal.

4:17So, how do we put it all together?

4:20Easy.

4:20First, we roll the lemon while pressing down on it to make sure there's lots of

4:24juice flowing inside.

4:30Then insert the penny on the right side

4:32and a galvanized

4:37nail on the opposite side. So simple, can we test it with the multimeter? That's a

4:43good idea.

4:50Our lemon battery is producing about one volt.

4:56Is that enough to power an LED?

4:58Not quite, but what we can do is link multiple lemon batteries together in series

5:03to increase

5:03the voltage. Excellent.

5:23We now have a total of four lemon batteries.

5:28Now how do we connect them all together?

5:32To connect batteries in series, we connect the positive terminal of one battery to the

5:36negative terminal of the one next to it.

5:38We'll use these alligator clips.

5:51Now the two remaining terminals can connect to our LED.

5:55Correct.

6:08Wow, it really does work.

6:15An LED powered by lemons.

6:17Not just lemons.

6:19Don't forget, Adabot.

6:20It's the lemon, the zinc nail, and the copper penny that work together to create

6:25the electrochemical reaction that generates current.

6:28And they sure do make a lot of juice.

6:30They sure do, Adabot.

6:32We'll never have to buy batteries again.

6:34Well, even though we did make a working battery, they're quite large, and they

6:38wouldn't fit in my multimeter, so for now I think we should continue buying

6:41batteries.

6:42Oh. Can we make lemonade instead?

6:45Sure. Why not?

7:10We'll see you next time.