Does anyone understand where electricity comes from?

[UWouldKnow]

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?

 

[Baluncore]

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.

Are electrons just in everything and by moving them you create electricity?

Yes. Moving electrons are an electric current.

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.

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.

 

[ISamson]

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.

 

[UWouldKnow]

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?

 

[Guineafowl]

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.

 

[Baluncore]

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.

 

[CWatters]

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.

 

[UWouldKnow]

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

 

[Guineafowl]

"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.

 

[phinds]

"... 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?