Does anyone understand where electricity comes from?

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Discussion Overview

The discussion revolves around the origins and behavior of electricity, particularly focusing on the role of batteries, the movement of electrons, and the implications of short circuits. Participants explore theoretical and practical aspects of electrical circuits, including concepts of current, resistance, and voltage.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that batteries move electrons to create current, raising questions about the source of these electrons.
  • It is suggested that electrons are present in all matter, and their movement constitutes electric current.
  • Concerns are raised about the implications of Ohm's law, particularly regarding resistance approaching zero and the resulting current behavior.
  • One participant describes a theoretical method of generating electricity by separating positive and negative ions, likening it to battery function.
  • Questions arise about the nature of short circuits, particularly whether they can produce infinite current and what limits this current in practice.
  • Some participants clarify that the finite resistance of the circuit and the internal resistance of the voltage source prevent infinite current flow.
  • There is a discussion about the conditions under which a short circuit might allow for a large current, emphasizing the role of the voltage source's capacity.
  • One participant expresses confusion about the limitations of voltage sources in supplying current, questioning the application of idealized values in real-world scenarios.
  • It is noted that real voltage sources have internal resistance, which affects the total current available in a circuit.

Areas of Agreement / Disagreement

Participants express a mix of agreement and disagreement, particularly regarding the implications of short circuits and the behavior of current in relation to resistance. There is no consensus on the nature of current flow in these scenarios, and multiple viewpoints are presented.

Contextual Notes

Limitations include the dependence on idealized versus real-world conditions, particularly regarding resistance and the behavior of voltage sources. The discussion does not resolve the complexities surrounding these concepts.

UWouldKnow
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I know that batteries move electrons therefore creating a current when there is a load. So if a battery is just for moving electrons, where do the electrons come from? Are electrons just in everything and by moving them you create electricity? If that were the case, why did I read somewhere that let's say resistance was approaching 0, then current would be approaching infinity, meaning that current would not actually be infinity but just dependent of how much the current source can produce. Current source? I thought a battery was just a voltage source and by moving electrons you create a current. That brings me to another question, can you make a current source without using voltage, because I know you can do that in theoretical circuits but can you actually make one and if so how do they work?
 
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UWouldKnow said:
So if a battery is just for moving electrons, where do the electrons come from?
Electrons surround each atom's nucleus. Electrons hold atoms together to make molecules. Some electrons are free to range widely among many atoms. That makes an electrical conductor.

UWouldKnow said:
Are electrons just in everything and by moving them you create electricity?
Yes. Moving electrons are an electric current.

UWouldKnow said:
If that were the case, why did I read somewhere that let's say resistance was approaching 0, then current would be approaching infinity, meaning that current would not actually be infinity but just dependent of how much the current source can produce.
Ohms law says that the current will be limited to voltage / resistance.

UWouldKnow said:
can you make a current source without using voltage, because I know you can do that in theoretical circuits but can you actually make one and if so how do they work?
Yes. An electron beam delivers electrons to a target.
 
Electricity could be made by dividing a space in two with one side containing positive and the other negative ions, when the sides connect, then an electric current happens. This is how a battery could work.
 
Interesting points. So what happens in a short circuit? Wouldn't the resistance be near 0 and since current is equal to voltage over resistance shouldn't current be infinity? What limits current from actually being infinity? So technically couldn't a short circuit somehow be a good way to create a large amount of current?
 
UWouldKnow said:
Interesting points. So what happens in a short circuit? Wouldn't the resistance be near 0 and since current is equal to voltage over resistance shouldn't current be infinity? What limits current from actually being infinity? So technically couldn't a short circuit somehow be a good way to create a large amount of current?

"What limits current from actually being infinity?"

The finite resistance of the overall circuit, the internal resistance of the source, and the increased resistance of the conductors as they heat up.
 
UWouldKnow said:
So technically couldn't a short circuit somehow be a good way to create a large amount of current?
In batteries, current comes from chemical reactions. The flow is limited by the rate of chemical reaction. The voltage across a short circuited battery is zero so the power available to the load is zero.
 
UWouldKnow said:
Interesting points. So what happens in a short circuit? Wouldn't the resistance be near 0 and since current is equal to voltage over resistance shouldn't current be infinity? What limits current from actually being infinity? So technically couldn't a short circuit somehow be a good way to create a large amount of current?

What do you mean by "good"?

There are no "ideal" electrical components. Even a copper bar has some resistance.

A short circuit will only cause a lot of current to flow _if_ the voltage source can supply it.

Aside: Super conductors have zero resistance but they also tend to stop being super conductors once the current exceeds a certain value.
 
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CWatters said:
What do you mean by "good"?

There are no "ideal" electrical components. Even a copper bar has some resistance.

A short circuit will only cause a lot of current to flow _if_ the voltage source can supply it.

Aside: Super conductors have zero resistance but they also tend to stop being super conductors once the current exceeds a certain value.

"A short circuit will only cause a lot of current to flow _if_ the voltage source can supply it. "

I'm confused about that, why would a voltage source not be able to supply enough current, cause 1/0 or 4/0 or even 100000/0 are all equal to infinity, according to ohms law the value of voltage doesn't really matter in this case
 
UWouldKnow said:
"A short circuit will only cause a lot of current to flow _if_ the voltage source can supply it. "

I'm confused about that, why would a voltage source not be able to supply enough current, cause 1/0 or 4/0 or even 100000/0 are all equal to infinity, according to ohms law the value of voltage doesn't really matter in this case
Only an ideal, fictional voltage source has zero internal resistance. In practice, there will always be some resistance in the circuit - very often, it's the voltage source's own internal resistance - the current in the circuit has to flow through the parts of the battery, chemical reactions have to happen, etc. You are confusing youself by applying idealised values (such as 0 ohms) to real-world situations.

Try shorting an AA battery with the current measuring option (on 10A scale) of a multimeter. The resistance of the meter leads and internals is negligible (but not zero). Let's say, 0.2 ohm. Since I=V/R, the current should be 1.5/0.2=7.5 A.

Do you get 7.5A? No. The AA battery is an imperfect source, with its own internal resistance, which drops the output voltage and limits the total current available. "Why would a voltage source not be able to supply [infinite] current?" There will always be resistance.
 
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UWouldKnow said:
"... why would a voltage source not be able to supply enough current ...
You would be asking a real world source to supply unlimited power. Don't you think that's a bit unrealistic?
 

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