# Circuit Playground: G is for Ground ## Video https://youtu.be/3MwgVp0oV7A Ground is all around! Join Adabot and Ladyada as they find electrical connections to the earth in a wide variety of places. # Circuit Playground: G is for Ground ## Transcript ![](https://cdn-learn.adafruit.com/assets/assets/000/074/530/medium800/circuit_playground_series_ground1.jpg?1555459384) 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? ![](https://cdn-learn.adafruit.com/assets/assets/000/074/531/medium800/circuit_playground_series_ground3.jpg?1555459435) 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. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/533/medium800/circuit_playground_series_ground6.jpg?1555459487) 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. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/534/medium800/circuit_playground_series_ground7.jpg?1555459505) Adabot: Like … Dirt? Ladyada: Yup - that’s Earth. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/535/medium800/circuit_playground_series_ground8.jpg?1555459519) Adabot: Pipes? Ladyada: Yes - very true. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/536/medium800/circuit_playground_series_ground9.jpg?1555459538) Adabot: A sink? Ladyada: Also connected to the Earth. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/537/medium800/circuit_playground_series_ground10.jpg?1555459552) Adabot: A tree? Ladyada: Well, yes, but it’s not conductive. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/538/medium800/circuit_playground_series_ground11.jpg?1555459600) Adabot: This rock? Ladyada: Uh-huh ![](https://cdn-learn.adafruit.com/assets/assets/000/074/539/medium800/circuit_playground_series_ground12.jpg?1555459615) Adabot: That rock? Ladyada: You bet! ![](https://cdn-learn.adafruit.com/assets/assets/000/074/540/medium800/circuit_playground_series_ground13.jpg?1555459631) Adabot: A fire extinguisher? Ladyada: No way. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/541/medium800/circuit_playground_series_ground14.jpg?1555459644) Adabot: A cup of tea? Ladyada: Not ground. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/542/medium800/circuit_playground_series_ground15.jpg?1555459663) Adabot: An airplane? Ladyada: Same deal. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/543/medium800/circuit_playground_series_ground16.jpg?1555459680) Adabot: A rubber ball? Ladyada: Not grounded. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/544/medium800/circuit_playground_series_ground17.jpg?1555459701) Adabot: A lightning rod? ![](https://cdn-learn.adafruit.com/assets/assets/000/074/545/medium800/circuit_playground_series_ground18.jpg?1555459714) Ladyada: Oh - most definitely. It doesn’t take long to complete this search. Ground is anything conductive that’s connected to the Earth. ![](https://cdn-learn.adafruit.com/assets/assets/000/074/546/medium800/circuit_playground_series_ground19.jpg?1555459747) Adabot: Doot-doot-doo Ladyada: Hey Adabot, back already? that was quick! Adabot: Yes - I found examples all over! ![](https://cdn-learn.adafruit.com/assets/assets/000/074/547/medium800/circuit_playground_series_ground21.jpg?1555459765) Ladyada: You might say - you covered a lot of ground. Adabot: Oh - zing! Good one, good one - that was good. # Circuit Playground: G is for Ground ## Learn more ![](https://cdn-learn.adafruit.com/assets/assets/000/074/551/medium800/circuit_playground_series_ground-symbols.png?1555464762 symbols for ground used in electronic schematics) ## What is ground? from [Wikipedia](https://en.wikipedia.org/wiki/Ground_(electricity)): > In electrical engineering, ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the earth. > > […] > > For measurement purposes, the Earth serves as a (reasonably) constant potential reference against which other potentials can be measured. An electrical ground system should have an appropriate current-carrying capability to serve as an adequate zero-voltage reference level. In electronic circuit theory, a "ground" is usually idealized as an infinite source or sink for charge, which can absorb an unlimited amount of current without changing its potential. Where a real ground connection has a significant resistance, the approximation of zero potential is no longer valid. Stray voltages or earth potential rise effects will occur, which may create noise in signals or if large enough will produce an electric shock hazard. ## What about circuits that run on batteries? ![](https://cdn-learn.adafruit.com/assets/assets/000/074/552/medium800/circuit_playground_series_battery.jpg?1555465628) Electronic devices that don't plug into a wall socket have a different type of ground usually called **common ground**. 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