ELI5
What is electricity exactly and how is it caused? I hear multiple things like it’s the movement of electrons, but that doesn’t make sense to me cause electrons are always moving. Isn’t it wave energy that travels by means of electrons?
I also don’t understand Voltage visually. I understand it’s the amount of joules in a Coulomb, but what would the difference be on a small level? What would be the difference physically and visually at 1volt to 1000volts on the atomic level?
In: Physics
*also don’t understand Voltage visually*
Don’t try. If you really want to understand then you have to let go of your conceived notions of the world because things get really weird fast and your understanding of the world from your experiences will cloud your ability to really get what is going on.
Voltage is a strange concept but it can be described with an allegory. Say you are standing with your arm out holding a baseball. The *potential* energy is the meter it will fall from your hand based on the force of gravity. It is potential because it is bottled up in your arm. Now, imagine there is a stack of marbles in a tube that reach up from your arm and touch your hand. Now rest your hand on that stack of marbles. The ‘voltage’ is the pressure exerted on that stack. Except, in actuality there is no ‘pressure’ and there are free electrons in that stack of marbles that do actually move as a result of this voltage. In real electricity, the conductive material is our stack of marbles, the marbles are electrons, and some of those marbles are free to move about and others are attached to atoms that from the structure of the conductive material.
Now, lets apply this concept. I have a stationary magnet with another magnet that can spin around the stationary magnet. I can spin the magnet by attaching it to a windmill or something. The voltage is caused by the magnets spinning, when the fields are far apart from each other there is a bunch of *potential* energy either in positive or negative. For us, positive and negative don’t matter, we care about the difference to zero. In order to produce voltage that wasn’t created by some other electrical force, we need some mechanical energy source, like the wind, a river, an ICE motor, whatever.
This is dramatically simplified, and I think my allegories are flawed if you examine those very closely. What I want to avoid is the idea that a wire is a tube full of flowing electrons, sometimes it behaves like that (which is why it is a popular comparison) but it isn’t quite realistic. Some people will say that it is like a tube full of water with pressure exerted on one end and on the other is some thing that will do work as a result of that pressure, it is kinda sorta like that but not really.
Electricity is little blue men. Amazing! Little blue men that live in the wires. The little blue men like to party. It turns out that there are amazing, wonderful parties in batteries, in the negative side. So, the little blue men have to drive to get to the party. That’s direct current.
Sometimes the men don’t want to drive. They want to party where they are, and do the hokey-pokey! One step forward, one step back, over and over. A party all along the wire, back and forth. That’s alternating current.
And so on. You should read “There are no electrons”, easily the best book on electricity and basic electronics ever written. They use the metaphor of little blue men to explain everything.
The easiest way to understand electricity – even though its a bit simplified – is to use the water analogy. Voltage is water pressure, current is flow of water, wires are pipes.
The electrons want to move from areas of high pressure (lots of electrons) to areas of low pressure (few electrons.) They do this by travelling down the wire like water through a pipe.
The electrons that constitute electricity are not strongly attracted to atoms so they can wander freely from atom to atom in the “electron sea” that surrounds metal.
Electromagnetism is the “effect” that is produced by electrical charges (+, -), like gravity is the effect that is produced by mass. Mass, charge, spin, color, etc., are properties of the basic particles of matter in physics, and they have forces and fields associated with them.
Anything that has a charge (one electron, many electrons, one proton, many protons, etc.) creates an electric field and a magnetic field, and whether you see “electric” or “magnetic” or a combination of the two depends on how you think the charge is moving.
Motion is relative, so if you’re on a train with someone wearing a bunch of electrons on their clothes, you’re seeing “static electricity”, but someone outside the train waiting at a crossroads may see a magnetic field, or a “current” (flow of electricity).
Comparing to gravity, Earth has a lot of material so it creates a strong gravity field. Other objects that move (fall or get lifted up) in this gravity field interact with it, and gain energy just from their position in the field (how high they are). They can convert this “potential energy” (energy because of their position within a field) to “kinetic energy” (energy because they’re moving) by falling down within the field.
Electromagnetism is also a field, so the same thing happens. Chemical reactions can strip electrons out of the outer orbitals of atoms (this is what a battery is), and otherwise electrons being forced to move inside an electromagnetic field (this is what a turbine does at the power plant), these create potential energy within the electromagnetic field. Voltage. The higher the voltage, the more the electrons want to move through the field (“fall” to zero “ground” level).
Compared to gravity, voltage is like “how strong the gravity feels at this position within the gravity field”. Sort of related to height, but also related to whether you’re 1 meter from the surface of the Earth vs. 1 meter from a black hole. Voltage is how strongly those charges (electrons typically) are being pulled by the electromagnetic field.
Now, one important difference between gravity and electromagnetism is that metals are just like any other material for gravity, but they’re special for electromagnetism.
Metal atoms form an ordered crystal-like structure, and the electrons in the outer layers can flow freely between the atoms, very little force is required to move them [like a river flowing between pebbles](https://www.abc.net.au/science/basics/img/Metallic-bonding.jpg). Metals conduct electricity (electron movement) very well, and we use them for that purpose. There is no equivalent material that does that for gravity (that we know of).
As an example of the opposite, plastic atoms arrange themselves [like this](https://www.sciencenewsforstudents.org/sites/default/files/scald-image/860_main_polymers.png), and it takes a high voltage to “pull” the outer electrons out and move them along the chain. Plastics, air, rocks, glass, etc., are all insulators, the electrons don’t flow unless there’s a very high voltage to pull them out and force them to jump from atom to atom.
Air is a gas, the atoms of air are far apart, so air is also an insulator. It takes a high voltage to force electrons to go from atom to atom through air, and that’s why a lightning bolt, when it discharges, it discharges A LOT of pent-up energy.
Electricity is a relative phenomenon. Charge is a static property of some particles, like the electron and the proton. These are not the same thing.
If you have an object with lots of unbalanced change (more electrons than protons or vice verse) it produces a static electric field in the region around it, even if that region is a vacuum. From any point outside the charged object, the strength of that static field can be measured, in volts. 1 volt is a small gang of extra electrons and 1000 volts is huge crowd of extra electrons. This is not the absolute voltage, it’s the differential voltage between the object with the crowd and the point in space.
Electrons can move through things that are “conductive”. Lots of things are poor conductors, like air, and a few things are good conductors, like things made of copper or gold. Electricity is “net movement” of the electrons. It’s not the electrons circling around and around their atom’s nucleus, only when they travel from atom to atom across the object. This travel is powered by the fact that electrons repel each other, if you put a free electron in a static electric field it moves away from the object with net electric charge.
This movement of many electrons, called a current, creates a magnetic field and heats the object being traveled through (unless it is a superconductor). Good conductors are heated less, allowing the electrons to get where they are going faster, leading to a rule of electrons taking “the path of least resistance”.
Electricity can travel through things that are poor conductors, if the crowd of excess electric charge is large enough. Lightning is an example of electrons flowing through air (a poor conductor) at such a high current that they ionize the gas molecules (making them a better conductor) allowing a huge current to travel to ground.
Lots of posts that definitely don’t break it down into layman’s terms. For your bit on understanding voltage; Electricity is comparable closely to fluid dynamics. If you know how water pipes work you can get a sense for electricity.
Voltage is “potential”, it’s like Pressure
Current/Amperage is “flow volume”, like flow volume or the width of a river
Basically with electricity, molecules have these electrons that wanna go from a high-“pressure” area to a low-“pressure” area. From a place with a lot of free electrons and charge, to a neutral one.
The pressure, or potential, or tendency for electrons to flow is called Voltage. The amount of electrons available to flow at any given time, or the amount backing the “pressure” is called current.
I just want to say that “electricity” is a very imprecise term. It is not a scientific term, it is a layman’s term. “Electricity” is a general way to refer to various electromagnetic phenomena, like sparks, light, and getting a shock when you touch a cable.
However, in science you have to use proper terms, like “current”, “voltage”, “potential difference”, “energy”, “power”, “electromagnetic radiation”, etc.
So that’s one thing, “electricity” cannot be defined exactly, because it isn’t scientifically defined. Now, if you are asking, “what is electric current?”, then that has an answer.
I only make this clarification because you are asking about different things. Current is one thing, voltage is a different thing, electrons is another thing, they are all related, but they are different. All together form the imprecise concept of “electricity”. Now you can proceed to read the other answers in this thread.
>electrons are always moving
Yes, but they are not always moving in one direction. When a lot of electrons move in one direction like a stampede, it is called electricity.
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