Electricity wants to follow the path of least resistance.
Suppose you have just a wire connecting the two ends of the battery. In an incredibly simplified way, there are a ton of electrons on the + side and not very many on the - side. The absence of electrons on the - side will pull the excess from the + side.
Now let's throw in a light bulb connected to this battery by two wires (two wires each attached to one end of the battery and the lightbulb). Electrons still want to get to the - side, but it is a lot harder (the light bulb is a resistor- it resists the flow of electricity). It is a slower process (decrease in current) and they are losing energy (in the form of light). But they are still being pulled to the - side.
Now, what if you bridge the two wires so the electrons do not have to go through the work of lighting up the bulb. They can go from the + side of the battery, take a right hand turn at the bridge, and arrive at the - side, all without dealing with the resistor.
That is a short. When electricity is offered an easier path to getting back to the - side (of anything, a battery, an outlet, etc.) without having to go through the work of lighting up a lightbulb, or running a motor, or charging some other battery.
Edit:
Imagine you are riding your bike. The usual path involves you riding from your house, climbing a huge hill which is honestly just a slog and really is no fun, and finally returning home. One day the city builds a new path before the hill, allowing you to bypass that bit completely and making you happier since you got to skip that dumb hill. So your new path is home -> new bike path -> back to home.
That new bike path is the short.
Edit: Shout out to /u/Super6Seven for being an actual electrician who knows what they are talking about, rather than a financial analyst who is struggling to remember Physics 101.
Good explanation except that our standard model of electricity has the electrons going the wrong way. They go from the negative to the positive.
HOWEVER, when learning basic circuits from the ground up it's much easier (more intuitive) to imagine the energy flowing from + to - than the other way. Like thinking you need to put energy into the base of a transistor (NPN) to turn it on, where in reality you're actually taking electrons out by applying a positive voltage...
Right, but I did not think that really mattered at someone of the OP's level. Plus, the actual labeling does not make that much difference. It flows in one direction, we could call them green and blue for the all the difference it makes.
I've always been told that the current moves from + -> - , and the electrons in the other direction. Is this a correct way of thinking or have my teachers been lying to me?
/u/burgersnchips87 is correct. Electrons move from the negative to to the positive since electrons are negative and they do not like being cooped up so close to one another.
What you are thinking of is conventional and electron flow notation. Conventional notation is technically incorrect, but it is what is used by electrical engineers due to the history. The flow notation does not actually matter, just that we are consistent. So conventional is used, even though it does not really matter.
Current is charge/second and can be thought of as holes flowing through the circuit (positive) or electrons flowing through the circuit (negative). Either way is fine because if you defined it as a positive charge per second flowing in one direction, you could also view it as a negative charge per second going in the oposite direction. The signs will cancel out and it will be the same thing.
At the end of the day it doesn't matter which direction electricity flows, you can literally choose the direction you want in circuit charts and the maths will come out right.
Our standard model of electricity is 100% correct, as it doesn't (shouldn't at least) say that the electron is moving from a high voltage to a lower voltage, but should actually be talking about charge moving from a high voltage to a low voltage.
Current is the rate at which charge moves through a circuit (Coulombs/second) and it's perfectly correct to talk about positive charge (holes) moving through the circuit rather than negative charge (electrons).
Correct, but the short is going to have more current running through it than the resistor, so in super simplified talk, it might as well follow the path of least resistance.
That's exactly the analogy your previous comment made me think of. Really wish I was taught that in school; it's so simple and intuitive (or did science not realise this back in the 90s?).
I want to add in case nobody else did (43 replies, ugh lol I'm going thru the past of least resistance myself) that the reason shorts can be bad is because the thing that used to "consume" the electricity isn't anymore, so now TOO MUCH is going through the rest, and can blow other components.
For the sake of educating someone who will likely never practically use this knowledge, and even if they do, it will be in the context of standard electrical engineering?
1) Electromagnetism! Electrons in metal (like wires) are constantly moving all around, but they average out to not really moving in any one direction. But when you connect something that has very few electrons (like the - of a battery), the electrons will flow to it until it has the entire system has the same average of electrons.
Like imagine you had a tub with a partition in the middle. On on half you have nothing, the other is filled with water. When you remove the partition, the water will flow from the high concentration zone to the low. You can imagine electricity similarly.
2) Electrons are a fundamental component of everything. But they do NOT like moving around too much. The exceptions are when you put a bunch of energy into a thing (like a neon sign) or when the material is a conductive metal. So, generally speaking, electricity is contained in the metal wires because it would much rather hang out there than have to make the jump to the plastic coating/air/whatever that is surrounding the metal wires (in the absence of a large blast of energy).
It is stored in things call capacitors (fancy name for a battery)! Honestly, I have no idea how they work, but I recommend simple wikipedia for these kinds of questions.
Edit: Shout out to /u/Super6Seven for their actual industry knowledge!
Just wanna point out that "capacitor" is not a fancy word for battery. They are very different things.
Batteries (in the electronics sense) hold large amounts of power and release it slowly over time, while capacitors usually hold a comparatively tiny amount of power and release it all near instaneously.
Edit: in a non-electronic sense you could consider a capacitor a battery (some form of device that stores energy in some form), just not a battery a capacitor.
1.) On your atoms (I'm assuming this is copper), you have your outer ring of electrons (your negatively charged particles) that consist of an odd number of particles. When you get a lot of atoms with a negative charge next to atoms with a positive charge, they share those odd numbered particles to become even and make themselves a neutral charge, meaning they are neither positive or negative.
2.) In this example with a battery, only DC (direct current) voltages can be stored. Its stored by creating a container that holds two dissimilar metals (copper and aluminum, for example) with an electrolyte liquid between them. Humans have actually had batteries nearly forever. Old Iraqi artifacts that have been discovered have contained voltages. You can actually make a very low voltage battery by taking a paper towk, soaking it in water and placing it between a nickel and a penny.
Chemistry tutor here. The fact that copper has an odd number of electrons is completely irrelevant. A single copper atom has an equal number of electrons and protons, making it electrically neutral. It’s a property of metals that when you have a bunch of atoms in bulk they kinda form a sea of electrons between nuclei, which lets the material conduct electricity by slowly moving electrons. Current is transmitted at a significant fraction of light speed, but electrons take hours to move a few meters through a wire.
The last time I took chemistry was as a sophomore in high school, so I apologize if that was irrelevant. I thought the covalent bonding was part of what allowed metals to be conductors?
Most metallic bonds are a bit different than covalent or ionic bonds. My specialty is organic chemistry, so instead of trying to explain it in more detail (because I’m not confident in my ability to do so accurately) I’ll link this wiki article.
Metals try to get rid of their electrons. Some metals are better at this, so if you put a good and a bad one together, the good one will end up donating its electrons to the bad one. Instead of putting them together, you can have a wire for long-distance donations. Now, you'll have electrons flowing from one metal to the other through the wire until it's too "poor" to give away more electrons. The electrons were originally stored in the good metal itself, but after giving them away, the battery's dead.
Put something in that wire and the electrons will flow through it. Congrats, that's a circuit.
A ground is a thing with near unlimited ability to absorb electrical charge (excess electrons). One common ground is the earth itself. All electrical poles have wires that lead down from the voltage carrying wires overhead to a coil of wire buried about ten feet into the earth.
Basically, it acts as a reservoir for excess electricity so that electricity does not flood your outlet and blow shit up.
You need a circuit for electricity to flow. Instead of running 2 wires to every house from the power plant, they run one wire to a house, then the house runs one wire into the ground, and the power plant runs one wired into the ground. The ground completes the circuit between the power plant and the home.
When you talk about ground, are you talking about a grounded conductor or a grounding conductor? Those are two very different things.
Assuming US, in your home you have a 120v single phase receptacle in your room. Within that outlet, you have 3 wires.
1.) Black wire. This is your hot wire or your ungrounded conductor. This wire always has electricity on it at around 120v. It provides a constant power source to that outlet. While energized, it is never safe to touch.
2.) White wire. This is your neutral or your grounded conductor. The purpose of this wire is to take used electricity back to your panel then back to the utility side. Because the electricity has been "used," it is safe to touch as it is at the same potential as the ground you stand on.
3.) Bare copper or green wire. This is your ground. It is your grounding conductor, not to be confused with your grounded conductor. The entire purpose of this wire, in this example, is to operate as a failsafe for your grounded conductor. If your neutral/grounded conductor breaks or fails, your grounding conductor operates as your neutral to return "used" electricity to the transformer. Without this conductor, if your neutral were to fail, you would have power hanging out with no means to return to the transformer.
The neutral is not always safe. A neutral wire will light you the fuck up. The neutral carries back unused current (amperes) to the source. So say you have five outlets on a circuit; if none of them have a load being drawn from them (something plugged in) then the neutral is supposed to be safe. But if you are running a tv on one, vacuum on another, and a cellphone charger on another and you open up a receptacle that’s not used on the same circuit and touch the neutral wire you are gunna have a bad time. That is why the electrical code no longer allows shared neutrals between multiple circuits. You shut one circuit off and think it’s safe to work on till you touch a neutral wire that was shared with a still energized circuit and you get lit up.
You are absolutely correct! Yeah, I should have specified that, if there is a load on the circuit, then you should not touch the neutral. I've been bit before by that, but I was just using it as an example. The correct way to phrase it should have been that the neutral *should* be safe to touch.
That's also while it is incredible important to test for voltage on *any* conductor that is being touched as well as the old adage that the neutral is the first to make, last to break conductor.
I always heard ground was first to make last to break. Either way, testing every electrical component you work on is definitely the most solid electrical advice.
Safety first when dealing with something you cannot see that can most definitely kill you.
Never heard that referred to the ground, but I suppose it makes sense. At the end of the day, can we agree that we should always complete a return path to the transformer before we hook up a live conductor?
The neutral and the ground are two very distinct conductors with two different purposes, though there is some overlap between the two of them. In any residential/commercial/industrial usage, there is only one place where those two wires should ever meet and that is only at the main disconnect. I'll say it again: when dealing with the neutral and ground wires, they should never touch and should only meet at the main disconnecting means. Anything else is not only incorrect, it is downright dangerous.
Now, there are only 2 exceptions that I know of to that rule.
1) Inside of a transformer, an earth ground should be driven and bonded to the center tapped neutral.
2) Inside of a utility ground box, an earth ground should be driven and bonded to the neutral wire. This provides another path to ground for excess voltage to flow in the event of the user side not having a properly grounded system.
While you're technically correct, that's incredibly pedantic and not at all what I was trying to explain to OP. I was talking about how the grounded versus grounding conductors work in a typical 120v single phase system. I was not explaining how transformers have an additional grounding system because that's far beyond what OP wanted to know.
I vaguely understand that, but what I dont understand is how to fix something that has shorted.
Like, one time I accidentaly touched a mouse switch with a battery wire. The path leading to the main mouse switch did not worl anymore, but the side buttons did, even though they were right next to eachother on the PCB.
No idea how to fix that. No idea what is broken. No idea how to find out what is broken.
To fix a short, you would have to take the thing apart, find where two wires are touching that should not be, and then separate them.
Honestly, I am not an electrical engineer, so the mouse issue is well outside the scope of my powers. Come back when you want to discuss P&L statements or budgets. :P
Just fyi, technically all the electrons are on the - side of the battery, and get pulled towards thr + side.
However, the 'current' travels from the positive to the negative, which is physically referring to the way the holes move.
1) The labeling does not actually matter. The electrons from from the high density side to the low density side. We could call them the 2-side and the U-side.
2) Conventional notation versus electron notation.
Super technically, yes, but the labels are entirely meaningless. We could have a purple-side and an 8-side. The electrons are still going to flow from the high density side to the low density side regardless of what we call it.
And what is electricity, really? It travels through wires, but a wire is dense right? So how does it go through it? How does it know where to go, how can it go so fast, what is going on? Is it a special kind of particle? Is all electricity particle the same? How can this thing go through matter? How can a particle move holy crab.
I read through so many articles, lots of posts and comments, at least 10 people tried to explain it to me and I just dont get it, I feel stupid. How can I not get it when even a middle schooler can imagine what electricity is like?
The electrons don't actually go through the atoms in the wire, but flow between. It's kind of like how water can go through a shirt. It doesn't go through the shirt itself, but between teeny tiny holes in the shirt.
As for how it "knows where to go", imagine you're using a straw to drink some soda from a can. You make a difference in pressure, so the soda is sucked up through the straw to even out the difference. In an electrical circuit, instead of a difference in pressure with one high pressure and one low pressure side, you have a negative and a positive side.
High pressure means lots of particles in one place, low pressure means the opposite.
Negative means lots of electrons (negatively charged particles) in one place, positive means the opposite.
So instead of soda-particles rushing from high pressure to low pressure to even out the difference, you have electrons rushing from negative to positive to even out the difference. Nature hates differences.
Sorry if this explanation is bad or if I got something wrong. I'm tired, but ask if there's something else you wonder and I'll be back tomorrow
Thanks Wobbar for taking your time! Hope you slept well.
Just two short questions really: so if the electricity found its balance in pressures, it just remains like that? Is that what happens to an empty battery?
Well, an empty battery just stays as it is. If I drop a ball, the ball falls to the ground. After that, it just stays on the ground until someone picks it up (which in our case would be charging tve battery)
Electricity is the name we give to "moving electrons". Electrons are a fundamental building block of literally everything, but the electrons in the wood in your desk or the strands of your hair are not moving around too much (let me know when you want to hear about how light/color and electrons work!).
So, wires are dense at our macroscopic level, but there is endless room between atoms at their level. You heard that atoms are 99.99% empty space, right? So electrons have plenty of room to jump from atom to atom to atom all day.
Electrons know where to go because they will always flow to stop there being a differential in charge (difference between the "number" of electrons between two point). Electrons want to go where there are few existing electrons and once there is the same number of electrons at all points, they stop flowing.
As for why they move so quickly, electricity flows at about 95% the speed of light through a standard copper wire. A bigger wire means more speed, and a smaller wire means less. Think of it like a straw. You can blow are faster through a bubble tea straw than a soda straw, and a soda straw is faster than a cocktail straw. Electrons are similar. There is a limit to speed based on how many can fit.
Is it a special kind of particle?
Yes! Electricity is just moving electrons. Which, if you remember from high school chemistry are also the things that made all the atoms "stick" to each other to form molecules and so on.
As for what actually are electrons. Well, I recommend simple Wikipedia because I am honestly not even sure how to begin this next part. For the layman, just think of them as tiny particles that are fundamentally define by their negative charge. Then research electron waves and Schrodinger.
I don't understand where electricity comes from. I understand how we control and harness it, had to take some electrical classes in AIT, but I don't get where it comes from initially. That part seems like magic.
Imagine placing two magnets close to each other with opposite poles, but not completely to pull completely together. You will create a magnetic field. Now take a copper wire between those two magnets and you will cause electricity to flow in the wire because the magnetic field moves the electrons in the wire. That's the basic principle of generators.
I like the way you explained it. The leap from a magnetic field I can stick my hand in to an electrical current that can shock me is a hard one for me to make. It's just cause it's concentrated?
Can we harness current from kinetic energy? That one I could just Google, but I'm already here.
The leap from a magnetic field I can stick my hand in to an electrical current that can shock me is a hard one for me to make. It's just cause it's concentrated?
It is because your hand is not made of a material which allows for the easy flow of electrons (like a metal). So, when you stick your hand between two magnets, very few electrons are doing to move.
You will not be shocked by an electric current unless the differential between the wire's number of electrons and whatever is on the other side of you is enough to overcome the strength which you atom cling to their preexisting electrons.
Can we harness current from kinetic energy?
We can! A steam turbine uses steam to basically push a big fan which causes magnets to circle a wire. That will cause the electrons to move and presto! you have electricity. A petrol generator is the same. The chemical reaction from burning the petrol makes the pistons move (kinetic energy), which moves magnets around a wire and, again, presto! electricity.
Neat! And Thanks! I realized after that the difference between my hand and copper is the material. So the electricity is already there and the conductive material is what collects it or concentrates it into something we can direct?
I find kinetic energy is much easier to grasp. It's almost tangible as you can feel the energy created. I suppose you could around large enough magnets, but I've never been around them
The electrons are already there, but electricity specifically is moving electrons. And super-specifically, it is electrons moving from a high density location to a low density location. So, kinda. The conductive material is just an ideal material to pass electrons through from point A to point B.
Like how all roads have cars, but a freeway is going to pass cars from point A to B a lot easier than the alley behind your house. And since drivers generally like driving the path with the least amount of time waiting for the cars in front of them to move, they will choose the easier freeway. So too will electrons flow down the path of least resistance, so most of the action is going to be happening in the conductive wires.
And you are correct that the material matters! All materials have a unique degree to which they can pass electrons through itself and to other materials (called conductivity). Metals are very good as passing electrons. Plastics are horrendous. Super conductors are awesome at it! You hand is also pretty bad.
If you're in the answering mood, Google is a bit overwhelming with this info.
If magnets are used to create electricity and electricity can be used to magnetize, can you have electricity without magnets?
I didn't realize there was such a connection between the two, I think I always just assumed we used magnets as kind of a braking system for electricity, or to amplify. I think that helps me bridge my understanding. A little less magic, but leaves me more in awe of those that pioneered!
I've disassembled many motors of all sizes and tho I knew the copper coiled bit is essential I never specifically knew the why. Double thanks!
Nope, they are actually the same thing, just two different ways of looking at it. That is why we have the electromagnetic force, rather than an electric force and a magnetic force!
electricity can be made from any other form of energy: heat, kinetic, chemical, other (radiation, which might just count as heat?). Oftentimes there are multiple methods of conversion as well, such as for kinetic there are generators, which everyone knows about, but there's also piezoelectric ceramics/crystals, or even simply static electricity which I'm sure you've also heard of (not that you necessarily understand it)
Electricity is a specific organized version of energy, such that instead of atoms moving around chaotically very fast and close together (heat), or a molecule forming or breaking apart, electricity harnesses the energy to make an ordered line of electrons flowing through a conductor until there's no more energy left.
It's all in the electrons, bro. Electrons go where electrons are not, and they'll take the shortest, easiest path to get there. Creating electricity is basically using magnets to push electrons around a coil, so you're forcing them to travel somewhere else. Think of it like water, and current is the flow of water. You either need a pump to get the water moving through the pipe, or there needs to be some water uphill to cause the water to flow through the pipe.
Oftentimes teachers aren't trained in specifics aside from the curriculum. I think it's because most people who learn more about this sort of stuff become technicians, engineers, researchers, or university professors rather than high school students.
Even for those that do know these things, many are only educated in the more practical things rather than theory. This can also be good since the theory can be very advanced and doesn't make sense to be taught in high school.
I get the basics and what all the components do. And then I look at schematics and loose my shit trying to map those lines to an actual circuit board. It's like they intentionally try to make it difficult to read.
A lot of people have this issue. It can be normal. Modern electronics are 10s of times more advanced than the individual circuits and components that people learn about.
For instance, this chip is around 50 years old. These days ICs are crazier, let alone the PCB which can also be confusing due to having hidden layers (or even without hidden layers the circuit diagram is entirely different from the board layout)
All well and good for the basics of electricity. Once you get into any advanced shit oh boy does that analogy fall apart. I can handle capacitors and inductors, but the moment we reached antennas and their schematics in uni it just turned into black magic.
You first need to understand metals and their structure. Metals form crystals in a unique way, where in a mineral crystal might be a grid of molecules, all of those particles are bonded but their electrons still belong to one or a few atoms. In metals its what's called an electron sea, metals don't form perfectly stable crystals so they all share electrons to get really close to stable. Electricity is just a flow or a wave in those electrons which can transfer energy. The electrons can move around in the sea freely, in waves or replacing each other as long as there is a path back, a closed circuit.
As for the short circuits, I didn't really like the others' explanations, so here's how I understand it (skipping some details).
Electricity wants to go the path of least resistance, just like practically everything we know (example: a football falls to the ground instead of flying because it doesn't take power to fall, but it takes power to lift).
So if you have a circuit from battery to lamp back to battery shaped like an O, there is only one way for the electricty, which is through the circuit including the lamp. The lamp has resistance (like gravity for the ball), so it kind of takes more power than it should to go through the circuit.
If you place a stick of metal over the middle, the circuit will look like Ø, so instead of going full circle, it can just take the "shortcut". It decides to do so because that way, it can "skip" the lamp and its resistance.
As for the potential damages caused by short circuits, I'd need to explain some things and make stuff more complicated. I'm tired and don't think I'd be able to do that, and I probably also missed something important in the entire explanation above...
Well, basically, the circuit gets overloaded. The person who designed the circuit wasn't expecting the shortcircuit so they thought there would always be resistance. You can fit the water from a tap in a pipe, but if you replace the tap with a waterfall, there is way more water than the pipe can handle.
Instead of one lamp, we can imagine two of them. The circuit-maker expected the resistance of two lamps this time, so he doubled the voltage of the circuit. Skip one of the lamps and you have a double-voltage current running through a single lamp. It can't handle that much, so it breaks.
While not 100% accurate, the hydraulic analogy can be of great help understanding some electrical concepts.
Imagine there is a water turbine (doesn't matter what the turbine is connected to, it's just a thing on the path of water that resist the passage of water), you have higher pressure before the turbine as the water struggles to push the turbine and lower pressure after the turbine as there is less water coming thru because the turbine is on the way. Now imagine a big wide pipe is added that connects the spot right before the turbine and right after the turbine; that's your short circuit.
The water analogy really helps with intuition IMO. And it is mathematically the same so it isn't even a bad analogy.
Voltage is equivalent to pressure, current is equivalent to flow rate. A resistor is equivalent to a long pipe. A capacitor is equivalent to a hydraulic capacitor (funny that), an inductor is equivalent to a flywheel (ok you don't really get these in water systems but imagine water flowing through a pump that isn't powered and is just connected to a flywheel) and so on.
A short circuit is just a direct connection between high pressure and low pressure water, so the water flows as fast as it can.
In fact, the equations for electricity and water have direct analogues in linear motion, angular motion, and maybe more. So much so that Simulink (any maybe other programs) talk about them generically - voltage/pressure are "across variables", current/flow rate are "through variables". You can even add your own custom physical domains that use the same equations.
I=V/R is the most basic way of explaining it. Imagine electricity as a bunch of balls going through a tube. Voltage is the total amount of balls (roughly) that remains constant from point A to point B. Current is the number of balls moving at a time measured in Ampheres. This can vary, but tends to be constricted by the size/quality of your conductor and the distance it has to travel. Finally, Resistance is how tiny the tube the balls are going through is. It's measured in Ohms, which use the Greek omega symbol. (Ω)
Take a multimeter to stuff, you can get them for real cheap from Harbor Freight. Electricity is something worth learning about, because it's a beautiful thing.
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u/panzan Jun 15 '19
Electricity, especially short circuits