Ladyada: Oh - hey Adabot. Howya doing?
Adabot: Oh - good. I was just wondering.
Ladyada: Wondering about what?
Adabot: Why do some power cables have two conductors, and some have three?
Ladyada: That’s a very good question Adabot. The answer is these three prong cables, are grounded.
Adabot: You mean - they’re not allowed to go out and play?
Ladyada: Oh no - not like that. See? On this connector, we have a third prong. And that’s the ground. We use these with appliances like this one for safety. If something goes wrong electrically inside, that extra dangerous electrical charge goes through the ground, and not through you! Which would cause a nasty shock.
Adabot: Ground? Like outside with all the dirt?
Ladyada: That’s right - the Earth is ground. So anything connected to the earth is grounded.
Adabot: Huh - so let’s say we’re talking about things that are ground. How many can we find just by looking around?
Ladyada: Are you kidding? That’s easy - we’re nearly surrounded! There’s a lot of things here that are very well grounded.
Adabot: Like … Dirt?
Ladyada: Yup - that’s Earth.
Ladyada: Yes - very true.
Adabot: A sink?
Ladyada: Also connected to the Earth.
Adabot: A tree?
Ladyada: Well, yes, but it’s not conductive.
Adabot: This rock?
Adabot: That rock?
Ladyada: You bet!
Adabot: A fire extinguisher?
Ladyada: No way.
Adabot: A cup of tea?
Ladyada: Not ground.
Adabot: An airplane?
Ladyada: Same deal.
Adabot: A rubber ball?
Ladyada: Not grounded.
Adabot: A lightning rod?
Ladyada: Oh - most definitely. It doesn’t take long to complete this search. Ground is anything conductive that’s connected to the Earth.
Ladyada: Hey Adabot, back already? that was quick!
Adabot: Yes - I found examples all over!
Ladyada: You might say - you covered a lot of ground.
Adabot: Oh - zing! Good one, good one - that was good.