A simple question about the flow of the electricity

[haruspex]

I believe I understand now. My picture of electric flow is much clearer. But still, how comes that the intensity of the current is constant? While passing through resitors, why doesn't the current "slow down" ? How are we sure that the flow is indeed a constant ?

Don't get me wrong! I understand that what comes in must definitely come out. But how comes that it goes out, at the same rate? Well, if two people enter a room through a door the two people will definitley come out sooner or later. Let's say that the first grabs a cup of coffee and the exits, and the second exits after he takes a nap. The electrons are very very dense, I get this. Is their tendency of repulsion that keeps them from gathering ?

It might help if you understand that the velocity of an electrical signal is much greater than the rate of movement of the electrons. Imagine electrons equally spaced along a wire. An extra electron is somehow added to one end. Repulsion will, at the speed of light, cause the next electron to start moving, which sets the next one moving, and so forth. Hence, though bunching may occur after some sudden event, like throwing a switch, it is so fleeting that it would be hard to measure.
For your analogy with people, you'd have to imagine them desperately trying to preserve their personal space.

 

[DorelXD]

It might help if you understand that the velocity of an electrical signal is much greater than the rate of movement of the electrons. Imagine electrons equally spaced along a wire. An extra electron is somehow added to one end. Repulsion will, at the speed of light, cause the next electron to start moving, which sets the next one moving, and so forth. Hence, though bunching may occur after some sudden event, like throwing a switch, it is so fleeting that it would be hard to measure.
For your analogy with people, you'd have to imagine them desperately trying to preserve their personal space.

That is a very good analogy, sir, thank you. So the presence of another person is very quickly noticed by the other person. He barely touches the floor with one toe and everybody is like: "go, go,go".

Good , you made this very clear and for that I'm deeply grateful. Another thing: when the electrons pass trough a resistor they must exit at the same rate, for the sam reason, is that correct ? I now completely understand that if there is no resitor the flow rate is definitely constant. But what about the flow through a resistor? Can you please tell me if the following thinking is correct?

I want to go back to the analogy I made earlier. I'm traveling up in a building, and I'm gaining potential energy. When I climb down the stairs, it takes me a while. But what if many many persons where climbing down the stairs, and my presence would be immediately noticed? That is, as soon as I put a toe on a step, the other persons notice and they immediately push each other, so that as soon as I'll be on a step with both feet, another person will have been on the floor level, right ? I now strongly believe that this is what happens.

And as off-topic I have two questions for you all:

1) do my questions show that I'm dumb? I'm worried that I don't gasp some concepts that fast. I mean...I solved electricity problems before, but I just applied formulas. I even used Kirchoff's laws without truly knowing what I was doing. Is that a problem?

2) did I annoye you? I really didn't mean that. I know I was a little bit inconsistent with my questions and I posted them in a chatoic fashion...

P.S. : I apologize again for my language, but I am not a native speaker. I am constantly learning! Thank you!

 

[nsaspook]

And as off-topic I have two questions for you all:

1: It's not dumb at all. You came to the problem with a first impression mental picture of 'mechanical electricity' energy used in many basic electronics 'viewpoint' courses in the world that's very electron/current/energy centric because it provides easy answers to common steady-state circuit parameter problems. That view is also reinforced by the common usage of 'current/amps' to represent 'power' in consumer and utility power goods. That mental picture had years of reinforcement patterns attached to it so it's not easy to just ignore or modify.

2: We have all had the same questions and most of us let you discover answers in your own way.

 

[DorelXD]

Thank you! I have one more question. As I said, I am now aware that the flow of the current must be constant. But there is still something a little bit foggy in my head. I know that when passing through a battery a charge gains energy and I understood the concept of voltage. In my old picture, this seemed very simple: a positive charge (conventional curent, I also understood that) goes from - to + and it gains potential energy.

The problem that arose in my head is the following: when we first start the circuit, an electron doesn't have time to make this journey through the internal circuit. The electrons that are close to the negative terminal "push" the electrons that are close to the positive one. But for a charge to gain an energy of, let's say 2 Volts, it must travel the whole length of the battery, right ? Then, what's happening inside a battery? Because in my head, an electron that is at the bottom, gradually picks up electric potential energy as it advance to the positive terminal. But obviously, until that electron will reach the positive terminal and will enter the external circuit, many others electrons will have left the internal circuit. How much energy have those electrons ?

 

[ehild]

Do not imagine that an electron travels along the whole path from one terminal of the battery to the other one. Outside the battery, you have a long row of electrons, pushing each other and this "push" travels very fast near the speed of light, while the electrons move forward quite slowly. Inside the battery, there are some chemical reactions which produce charge on the electrodes. The material of one electron dissolves in the electrolyte in form of positive ions, leaving electrons behind and making the electrode negative. At the other electrodes, positive ions deposit on the electrode removing electrons from it and making it positive. No need to travel through the battery... The speed of the chemical reactions determine how big current the battery can supply.
ehild

 

[DorelXD]

Oh my god, this is amazing. The physics is beautiful! It can be a pain if you don't understand it, or if you don't ask the right questions, or if you don't have a good physics teacher. Thank you all! You guys really helped me to understand. I am now 90% convinced that this is the way thing are. The rest of 10% is up to me; I need to convince and reconvince myself. I will read this discussion from the beginning to the end, and I will review what you told me. Thank you again!