What is a ground? What is a happening to need a ground?
In: Physics
It’s a wire connected in some way to the earth so that if something goes wrong in a circuit it doesn’t burn your house down. There’s more to it, but that’s the basics!
Grounding helps stop an electrical charge from building up (which can make heat, which can lead to a fire), and it can help neutralize a person’s charge which is important when dealing with things like electronics which are sensitive to electricity and can be fried/damaged if they take a static shock directly.
Ground is your reference voltage and is always at zero. All voltages in a system are measured relative to their ground.
There are many types of electrical ground. There’s EGnd or Earth Ground which eventually ties back to a long metal pole driven into the ground. There’s DGnd or digital ground which the digital signals in a system will be referenced against. There’s AGnd or Analog ground which the analog signals will be referenced against
Your USB phone charger has a couple pins in the USB cable referred to as Ground. They’re completely isolated from the metal rod that provides Earth Ground for the outlets in your house, they’re just ground for the USB power and data signals.
Everything in nature, including electricity takes the easiest path to get from point A to point B. Normally electricity is contained within hot and neutral wires. However when something goes wrong, the electricity can escape this natural path, and has to go somewhere. The ground wire makes it more likely that the electricity goes safely away from you and into the ground, rather than into your body.
This is how lightning rods work, they provide a quicker path for lightning to get where or wants to go, rather than hitting randomly and causing problems.
“Ground” is an electrical path to something (typically the actual earth) that is always at 0 volts and can take electricity being sent through it at any time. In your home the ground connections are always working as intended no matter what the power company does.
Grounding is a safety feature. Any part of an electrical device that is made of metal but should not be actually carrying electricity should be connected to ground. Eg: your computer’s case, your stove, and the conduits in the walls and ceilings etc that electrical wires are connected by.
In the event of something going wrong (eg: wire carrying voltage comes loose or other damage, maybe from heat) these areas could become electrified. If someone touched it they could be electrocuted, and there could be unintended heat production. Instead the electricity flows to or from the ground, and in all likelyhood trips the fuse/circuit breaker as a result. The power has shut off and it’s safe again since the voltage is back to 0 thanks to the ground connection still being there.
Grounding something means bringing it’s electrical charge back to being the same as the Earth /ground.
The Earth carries a negative electric charge of roughly 500 thousand Coulombs and when you stand on the Earth your charge is the same, hence you don’t feel it and there’s no flow of electricity between you and the planet. When something is ‘electrified’ it means it has a charge that is more or less than negative 500 thousand coulombs.
In Circuits 101, ground is the exact middle point between positive and negative in a circuit. Positive pushes and negative pulls and the ground area is where the current (moving electricity) stops being pushed and starts being pulled.* Since the positive and negative have equal strength, the voltage (electricity force) measured in that area is 0.
In engineering, the current is never supposed to make it to “ground” ideally. That’s because the “ground” in this context is actually an emergency exit current takes to avoid danger when something goes wrong. Instead the role of midpoint is played by something called the neutral wire.
*technically, current is being pushed and pulled at the same time always, but the other stuff that goes on in circuits makes this more complicated.
So you have a full circuit. Power source lead wire (wire hooked to positive of battery/power source) a load(light motor or whatever uses up the voltage) return lead (hooks to negitive side of battery) and ground (negitive side of battery) sometimes ground can be a frame on a motorcycle that is hooked to the negitive side of the battery
Take the earth is a giant neutral body, where there will never be any charge despite any flow of electrons out of or into the earth. A ground is simply when a electricity-conducting material is connected directly to this earth. Then, the material is known as grounded. The ground plug in your sockets already do this.
Usually the ground pin on your plugs are connected to the casing of your electrical appliance, especially when it’s made of an electricity-conducting material, like metal. That’s why Samsung phone chargers (at least in the UK) have plastic ground pins that don’t do anything, since the charger system of a smartphone has a non-conductive material on the outside.
The ground is there for a good reason. If a fault happens, say the live or hot wire is exposed and touches the metal casing, electricity is shorted through the casing, since electricity always takes the path with the lowest resistance. Without ground, this metal casing will become ‘hot’, and anyone who touches the casing will get an electric shock. The ground wire prevents this by allowing the electricity to flow from the casing to ground. As the resistance of the ground wire is low, this results in a huge surge of current through the live wire, casing and ground wire. This is why the appliance also includes a fuse placed on the live wire, which blows in the surge of current, opening the circuit and preventing the casing from going live.
My explanation isn’t the best, but I hope this helps.
Something that’s so big that if you put a charge into it, it dissipates almost entirely. Think of ground as the ocean. If you put a cup of the strongest acid in the world into the ocean, then mix it all up, the ocean is still pretty much the same ocean.
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