The basics of basics.

[DeafeningSilence]

This question has been a little annoying from the start, and I cant get anywhere without knowing and fully understanding how these things work, by these things I mean...how current flows through a circuit, from the most basic circuits, to more advanced, and as well as other need-to-know assets which hopefully some of you could supply me with.

The way I see this is as follows: Electrons - being negatively charged - move from a negative region, to a positive, my examples use batteries...why? I dont know, probably because another problem had risen when I heard that due to an electrochemical reaction batteries have charged particles on both terminals, I sort of knew that already, but not so in depth. So I dont really know which way the electrons move, or particles move, or where they go and if they need to meet up somewhere at the same time...

I have read over Kirchoff's law, but am unfortunately still in the void here. I know Im not thinking the way one is suppose to, If some of you could help clear that up, that would be great.

Note: If you could also explain if the rate of current is even a factor...meaning in the second picture I've provided, if electrons do indeed move from negative terminal to positive, then why would the location of the output, or even the battery not matter? What I mean with this is, no matter the location of the output - be it a lamp or LED - the battery, (or source), applies electric current to that output. This problem with my method of thinking is a little hard to explain...

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[MikeMl]

Read this thread.

There have been several similar threads. Search for "electron current", "conventional current"

You will be a lot happier, and a much better electronic-er if you forget about electrons.

 

[crutschow]

The way I see this is as follows: Electrons - being negatively charged - move from a negative region, to a positive, my examples use batteries...why?

Electrons repel each other. Otherwise you'd have all the electrons in the universe is one big lump. So when there is a voltage generated, such as by a battery, it indicates there are a larger number of electrons on one terminal as compared to the other. When you connect a conductor between the two terminals, the electrons will flow to try to equalize the charge. Since the battery continues to generate voltage due to electro-chemical activity, the current will continue to flow until the battery is discharged.

You can place a load, such as an LED, anywhere in the conductive loop and it will light from the current. The physical location makes no difference as long as it's in the loop.

That being said, as Mike suggested, just think about current flow in a circuit as going from positive to negative, as compared to electron flow, which does the opposite. Current flow is easier to understand, and it gives you the same results, at the circuit level, as electron flow. You only need to worry about electrons if you are discussing the theoretical operation of a vacuum tube (valve) or semiconductors.

 

[DeafeningSilence]

Well, in a way, I am trying to understand the theory behind how it works. Lets take a more complex schematic for example with multiple lines/wires branching off in several directions, If a battery is still the input/source, how would one know which way the current is flowing, or which branch it starts off at. I can understand that it does want to go from negative to positive, but in a case where there are multiple directions, that's where my ideology gets messed up a bit, because in a simple and single loop schematic like the one I have provided, there is only one direction of...traffic, from negative to positive, but if there are several wires branching off in different directions, I don't know where to start or end. That's sort of more what I was trying to get at.

 

[MikeMl]

Read up on Kirchoff's Law. Kirchoff used conventional current; not electron current.

 

[PatM]

I could never understand the intensity of feeling when comparing Conventional current to Electron current.

A engineer who was teaching a ham radio class, years ago, was livid when he discovered the class I was teaching was learning electron current.
He learned Conventional in school
I learned Electron in a Army radio repair school.

As long as you learn one or the other, and don't mix them there is no problem.

 

[crutschow]

Well, in a way, I am trying to understand the theory behind how it works. Lets take a more complex schematic for example with multiple lines/wires branching off in several directions, If a battery is still the input/source, how would one know which way the current is flowing, or which branch it starts off at.

It branches off according to the resistance in each loop and and it (conventional current) always flows from positive to negative in each branch.

Let's use a water analogy. Suppose you have a pump (battery) and it has several pipes branching off from its output. The flow in each branch (current) would be proportional to the pressure (voltage) and the size of the pipe (resistance). If you can visualize the water flow in the pipe, then you should be able to visualize the current flow in conductors.

Now when you have numerous branches, than it may be too complex to solve with simple calculations and you would have to use Kirchoff's law to generate the equations to solve for each loop current. (I'm lazy so I just use a Spice simulator such as LTSpice to calculate the currents.)

 

[Sceadwian]

I'm sorry but please, no water analogies, electron flow does NOT work like water in metallic conductors and it's even more complex in semi conductor substances and for ionic flow in liquids and gasses. In a thick wire with low current it might take days hours weeks months years or more for a single electron to actually go from one end of the wire to another, even with high DC currents, AC currents individual electrons will NEVER go from one end of the cable to the other, however huge amounts of energy will be transferred. It's more like waves in water. On the proper scale the acoustic transfer of sound waves through a pipe (including echo effects) are more useful for electrons going down a wire.

 

[crutschow]

I'm sorry but please, no water analogies, electron flow does NOT work like water in metallic conductors and it's even more complex in semi conductor substances and for ionic flow in liquids and gasses. In a thick wire with low current it might take days hours weeks months years or more for a single electron to actually go from one end of the wire to another, even with high DC currents, AC currents individual electrons will NEVER go from one end of the cable to the other, however huge amounts of energy will be transferred. It's more like waves in water. On the proper scale the acoustic transfer of sound waves through a pipe (including echo effects) are more useful for electrons going down a wire.

And I'm sorry you don't like the analogy but I'll stick with it. I think it helps the visualization process for people who have a problem with understanding simple DC current flow in wires.

And water flow in a pipe IS like electron flow in a conductor. How fast the electrons actually move in the conductor is irrelevant. What's the difference if it takes a second or a year for a particular electron to travel down the length of a wire? It's still flowing. The analogy isn't concerned about the speed of the electrons or the speed of the water molecules. Certainly it doesn't work for complex AC circuits or flow in semiconductors but that's beyond the scope of the analogy.

 

[Ratchit]

To the Ineffable All,

The electromagnetic field that drives charge carrier movement establishes itself at the speed of light, but the actual charge carrier movement (drift) is very slow. High amounts of charge are moved because the charge carrier that leaves the conductor is not the same charge carrier that enters it. So huge amounts of charge can be entering a conductor and the same huge amount leaving at almost the same time. Nevertheless, they are not the same charge carriers. It is analogous to a hose full of marbles; put one marble in one end of the hose, and another pops out at the other end very quickly. It is not the same marble, however.

Ratch