Eli5: how does electricity move? And, if electricity is electrons, does that mean that electricity has mass?



What makes electricity want to move? And when it does, is it the same electrons along the way? Or is it pushing electrons out of atoms in like a domino effect?

In: Physics

In AC, the current just oscillates back and forth. In direct current, yes electrons are sent down a wire or some other conductor. Electrons have a very minor mass almost too hard to measure.

Electricity (or more properly, electric current) is not electrons, it’s the *flow* of electrons (in the same sense that a current in water is not water, it’s the *movement* of water).

Current is created by a difference in potential (a “voltage”) between two points. Simply put, electrons want to move closer to one side of the system. So the electrons closest to that side move towards it, and then the next-closest electrons move into the area they leave behind, and so on. Imagine a bunch of people lined up for something: the first person in line moves, which lets the second person in line move, and so on. To extend the water analogy, a voltage is like a difference in height: water flows downhill, electricity flows “downvoltage”.

This can’t sustain for very long by itself, because electrons want to spread out. So there’d be a very slight initial motion, but then the “downvoltage” area would be too packed. (This is what happens when you get zapped by static electricity.)

Instead, electricity in everyday objects flows in a *circuit*: some outside source of energy (like a battery) is pushing electrons along, and they move in a loop in one direction. The water analogy here is a fountain: water flows down from the top of the fountain to the bottom, but the water doesn’t run out because a pump raises it back to the top again. So yes, it is the same electrons, and they are sort of pushing one another in a domino effect.

(What I’m describing here is *direct* current – the electricity that comes out of your wall is actually *alternating* current, where the flow of electrons goes back and forth. Alternating current turns out to be more convenient for engineering purposes.)

Electricity is one way to describe an electric current. An electric current is the movement of an electric charge. Electrons are all negatively charged and repel each other. A high concentration of electrons in one place will want to spread out to areas of low concentration, like food dye in a cup of water.


Magnets are the usual culprit for creating areas of high concentration, like a generator which burns gas to spin a magnet which ‘herds’ electrons in a particular way around a coil of wire, causing them to group at one end. Then you can plug in your light and the electrons will yolo thru the light to get to the other end of the coil where there are few electrons.

The thing that makes electricity want to move is called “electromotive force” and is typically described using “volts”. In direct-current or DC systems, you’re getting a stream of new electrons into your wire or device. In alternating-current or AC systems, you’re getting (kinda) the same electrons moving back and forth, like a saw might.

You could say that electricity has mass, but “electricity” is not a well-defined term in common use. It could be referring to electric charge, which cannot exist without matter, which has mass. Or it could be referring to electric current, which is just really describing the motion of those charges (no mass).

It is definitely like the domino effect. Each individual electron moves relatively slowly but the way they push each other happens so quickly that on the whole, electricity moves near the speed of light.

Electricity moves because it is pushed by electric fields. This is basically the same as you using a magnet to push another magnet around on the table using its magnetic field. If you have a long chain of magnets then you can push on one at the end with your handheld magnet and they will all push on each other until the one at the other end moves.

These electric fields can come from a variety of things. A capacitor can have an electric field that exists from having a lot of electrons inside it. Like a glass of water on the table, the water wants to spread out and if you put a hole in it then the electrons will push each other out and away.

A battery is like a pump that circulates water around a tube. It takes water (electrons) and just pushes it out the other side so that it travels around again. A battery does not actually have electrons moving through it but it does have whole atoms (ions) moving through it which do push electrons out one side and suck them in the other side like a pump.

Finally, a generator also makes electricity, and that works exactly like a water wheel or a paddle wheel. The paddle will spin around and push on the water (electrons) with its paddle just like the generator spins around and the electric/magnetic fields push on the pool of electrons.

I always think of electrical power like hydraulics. Voltage is pressure and current is, well, current. The pressure travels a lot faster than the actual water.

Whole lotta posts and few come close to ELI5, likely coz electricity is some weord dark magic shit. Here’s my attempt.

Electricity is what happens when electrons move in one of two ways – jiggling or flowing.

Both of those involve electrons jumping between atoms. I won’t get too far into the specifics there, suffice it to say that for some atoms, the outer electrons can jump ship, but doing so leaves a nice lil hole for a new electron to slip into.

Jiggly electricity is called Alternating Current. That’s when the electrons are going back and forth between the same atoms.

Flowing electricity is called Direct Current. That’s when the electrons are zipping around a circuit. Sidenote, a circuit means that it’s a closed loop, so the eelectrons will inevitably end up back where they started eventually.

The important thing for your second question regarding mass is that at no point in either of those procedures are new electrons added to the circuit, so no new mass is added.

So, while it’s true electrons have mass, you’re not gonna make something lighter by switching the power off.

(there are some edge cases to this, like capacitance, whoch is ebyond the scope of ELI5)

Imagine you have a tube of marbles laying horizontally.

If you push a marble on one side, a marble falls out of the other side. It’s not the same marble.

Electrons do have mass. Electricity is a force. Specifically, it is part of the electromagnetic force.

The electrons do physically migrate within the wires but so incredibly slowly that the effect is negligible for most practical purposes. we’re talking like inches per year in your household wiring.

as for what motivates them, they repel each other due to the electrical force, which is fundamental. it just sort of is, like gravity. The upshot is that if you can get an excess of them in one place then much like a gas under pressure they will want to “squirt” out. This is the spark you get from static electricity. The electrons are jumping away from you (or towards you depending on your charge state). a battery is the same, it has an excess of electrons at the negative terminal, and an electron deficit at positive terminal. Yes, electrons flow out of the negative terminal of a battery. Scientists assigned the terminals names before they understood the physical motion of electrons.

And yes electrons have mass but it’s so vanishingly small that for most practical purposes they can be considered mass-less. You can’t practically weigh a battery to see if it’s charged, e.g.

Electricity which is flow of electrons simply moves by potential difference between two points. Difference of potential between two points causes it to move.

For instance, Suppose there are two wires, one side of each wire is connected to battery. And other sides wires are connected to a bulb. Black wire is connected to negative terminal of battery and red wire is connected to positive terminal of battery. There will set up potential difference between both terminals of battery. If the positive terminal has higher potential and negative terminal has lower potential then electric current through battery moves from positive terminal (higher potential) to negative terminal(lower potential) passing through wire to the bulb.

And the reason behind potential difference is that when a **voltage** is connected across a wire, an electric field is **produced** in the wire. Metal wire is a conductor . Some electrons around the metal atoms are free to move from atom to atom. … This causes a **difference** in energy across the component, which is electrical **potential difference** .