Ladyada: Hey Adabot - did you see any of my AA batteries arou -- ?
Adabot: Oh hi Ladyada - I was just thinking about all the energy is stored in these batteries … just waiting to be used! … [tilts heads, mesmerized]
Ladyada: Yah … batteries are pretty cool …
Ladyada: … and they’re even better when I use them to power my multimeter
Adabot: Affirmative - batteries allow us to use electricity on-the-go, without needing to plug into a wall socket. Very handy … But there is one thing I don’t quite understand.
Ladyada: Oh? what’s that?
Adabot: Ladyada how *are* batteries filled with electricity in the first place?
Ladyada: Well batteries aren’t exactly filled with electrical energy, they’re filled with a few different things that work together to *create* electrical energy.
Adabot: Wow - you mean like little machines inside that generate electricity?
Ladyada: Umm … sort of … I think we better look this one up.
Adabot: Agreed! Accessing database “batteries”!
Ladyada: Thanks, Adabot. There are 2 important parts of a battery - the positive … & negative terminals. Connecting these 2 points to a circuit allows electrical current to flow from one terminal to the other
Adabot: Current, which we measure in amperes!
Ladyada: Exactly. And if we looked inside of a battery, we’d see something like this …
Adabot: Huh - how does that make electricity?
Ladyada: Well a battery uses *chemistry* to produce electricity - we call it an electro--chemical reaction.
Adabot: Ooh - sounds powerful!
Ladyada: It definitely is. Each terminal is connected to a different kind of material inside the battery. The material connected to the negative terminal has *lots* of extra electrons.
Adabot: looks pretty crowded in there!
Ladyada: Yup - it’s so crowded, that those electrons all want to go somewhere with more space for them to move around in.
Ladyada: Lucky for them, the positive terminal has lots of empty spaces for more electrons to fit into.
Adabot: Oh - so why don’t they jump over to the positive terminal with all those empty spots?
Ladyada: They can’t do that because the battery is filled with a special chemical called an electrolyte.
Ladyada: And electrons have a really hard time trying to move through electrolytes.
Adabot: That sounds awful! -- If they can’t move through the electrolyte, how will they ever get to their new homes over on the positive terminal?
Ladyada: By travelling through a circuit! When we connect a circuit to both terminals of a battery we give electrons a new way to get to those nice open spots over on the positive terminal.
Adabot: And they travel through all those different parts of the circuit to get there?
Ladyada: Yes - and they make lots of things happen along the way.
Adabot: Oh - you mean, like lighting up an LED. or making a motor move!
Ladyada: Exactly - and it all starts inside the battery.
Adabot: I was right - batteries are powerful! They must be very difficult to make.
Ladyada: Actually - we can make our own battery right now. It’s easy.
Adabot: Awesome! I’ll go get my chemistry set!
Ladyada: Wait -you don’t have to - we’ve got everything we need right here.
Adabot: A Lemon?
Ladyada: That’s right - the juice inside of a lemon can be used as an electrolyte. This galvanized nail is coated with zinc and we can use that as our negative terminal. And this shiny copper penny will make a good positive terminal
Adabot: How do we put it all together?
Ladyada: First we roll the lemon while pressing down on it to make sure there’s a lot of juice flowing freely inside.
Ladyada: Then insert the penny and nail. And we’re done.
Adabot: You were right - that *was* easy! Can we test it out with a multimeter?
Ladyada: Yup - good idea
Adabot: Our lemon battery is producing about 1 volt. Cool! Is that enough power to light up an LED?
Ladyada: Hmm - not quite. But we *can* link multiple batteries together to increase the voltage.
Adabot: Now we have four lemon batteries.
Adabot: But how do we link them together?
Adabot: Now the two terminals that are left unconnected are the ones we connect our LED?
Adabot: It works! An LED powered by lemons!
Ladyada: Not just lemons - don’t forget - it’s the lemon, nail and penny that are working together to create electrical current.
Adabot: Right - they make a great team!
Adabot: This great - with all these lemons, we’ll never have to buy batteries again!
Ladyada: Well - I don’t think we could fit a lemon inside my multimeter. We’re still better off using regular batteries.
Adabot: Oh …
Adabot: Can we make lemonade instead?
Ladyada: Umm … sure, why not?