Yes, this was exactly the case as I remember it now that I am reminded of why we were told about this convention difference. The focus was always what was happening to electrons at the junction points of the cell, and any other consideration of current was secondary to that.
I don’t understand because people are saying it doesn’t make a difference, but then saying the lightbulb would light later/sooner given the relative distance between the negative and positive terminal. If you are basing your calculations on the idea that current flows positive to negative then you will be wrong on the time it takes for the bulb to light. Maybe it doesn’t make much practical difference but it still seems incorrect and would make a difference if designing circuits with wires of huge distances. It seems I’m either getting conflicting info, or interpreting their answers incorrectly.
“Current flows positive to negative” is not the same as saying that the current flows starts at the positive end and then propagates to the negative.
I’m not sure where you are getting this impression. Can I ask you to quote where you saw this?
The current doesn’t start flowing from the battery when the circuit is closed. The current is always “wanting” to flow at all points in the circuit. No matter where you put your switch, current will be flowing through it as soon as you close it.
Want to point out again that the distance between the switch and the bulb would make a difference. And it would make the exact same difference if the switch were on the positive or the negative side of the bulb.
So, if you have the positive terminal of a battery connected to a switch, that then goes to a light, which then goes back to the negative terminal, then if you turned the battery around (assuming that your light bulb doesn’t care about the direction, like an LED), then it will operate exactly the same.
If you added in more wire between the switch and the bulb, however, it would take longer. So, say you added about 200,000 kilometres of wire between the switch and the bulb. Now it’ll take about a second to turn on. (Assuming your battery push the circuit, which is unlikely.)
At the same time, if you had your ridiculously long circuit, but the switch and the bulb were right next to eachother, then the light would turn on the instant you closed the switch, no matter how far the switch and bulb are from the battery.
Of course, a wire of that length is no longer a “weak capacitor”, so assuming that your power source can push it, expect some drama when you close the switch.
It’s not a matter of practical difference, it is a matter of zero difference.
I’ve skimmed through the replies, and I don’t see anything conflicting. Maybe if you point out what posts you see as conflicting, we can see where we are not being as clear as could be.
Part of the reason for apparently conflicting answers is that there is a lot of oversimplification here, and the simple case of “how does charge move down a wire” is not quite the same scenario as “what happens when I turn on a switch with a light bulb in the circuit”.
As Ruken said, current flowing positive to negative is not the same as saying that current starts at the positive and flows to the negative.
Again, oversimplifying, if you connect your light bulb to a power source with a loop of wire that is a light-year long, the electrons start to flow in one direction around the loop and “holes” start to flow in the other direction around the loop. The light bulb is going to light equally quickly regardless of whether it is attached to the positive side or the negative side.
In reality, when you start getting into long wires, the resistance, inductance, and capacitance of the wire FAR outweigh any relativistic effects.
Whoops, been busy. You said in post #5:
If your wire is one light-year long, and the charge is traveling at 0.7 times the speed of light, it will actually take about 1.4 years for you to get shocked
Wouldn’t that delay in being shocked also be a delay in lighting a light bulb?
Also a follow up if you will- if the flow of current doesn’t matter, why say it flows from positive to negative at all? Is it so you know the direction of the magnetic field around the wire?
The direction of current is very important for many things. Examples include semiconductors (transistors, diodes, SCRs, microchips, LEDs, etc.), DC motors, and DC solenoids.
Almost entirely you don’t. You don’t say it flows from positive to negative. There are only a few situations in which the direction of flow is important, or even in which flow is important.
I work with Direct Current, and with Electronics, both areas in which it is important to mark things as positive and negative, so that you know what to connect to what, and which way around to put things, and what you expect to see when you measure, but the fact that something flows is of no importance, and the idea that anything flows from positive to negative is of no importance.
Even when I work with magnetics, or with fields, where the flow and direction of flow is actually meaningful, I don’t have to think about what the direction of flow means: I only have to think about what the effect of current is.
This whole thing about current ‘flowing’ is something that is taught in schools to help you get your mind around the math, and the fact that nothing happens in a circuit if the circuit is broken – and even that is deeply confusing to electricians when they look at RF circuits.
And when they tried to anchor this pedagogic model in reality by teaching ‘electron flow’, they found it had the opposite effect: the ‘electron flow’ distracts people from the ideas (and math) of electricity.