# General question about electric flow

#### bibble235

Joined May 29, 2018
54
Excuse the diagram new to the tool

I understand you need to have a path to ground for something to work and now understand roughly the flow of electrons. My question is when you do not connect to ground, is there no flow at all. No leakage from the valid flow which is connected to ground. Sound silly as I don't need to understand just follow the rules but cannot help wondering.

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#### WBahn

Joined Mar 31, 2012
28,192
Ground has nothing to do with it. You need to have a complete circuit in order for current to flow. The only exceptions are cases where large static charges can build up, such as prior to lighting strikes, or the strikes themselves (although, taken together, you have a complete circuit, it's just that the current flows are separated in time).

#### LowQCab

Joined Nov 6, 2012
2,940
In your picture, the top-LED would blow instantly,
because there is nothing to limit the Current that would flow through it.
The second LED would do nothing.

A "Circuit" is just that, it's a "Loop",
if the Loop is broken, no Current will flow.

A Power-Supply, or a Battery, has 2-Terminals,
one is "pushing-out" Electrons, and the other is "pulling-in" Electrons.
This is what makes Current flow.

Usually, but not always, one side of the Power-Supply is connected to "Ground" or "Earth".
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#### WBahn

Joined Mar 31, 2012
28,192
In your picture, the top-LED would blow instantly,
How is it going to blow if the positive terminal of the battery isn't connected to anything?

#### LowQCab

Joined Nov 6, 2012
2,940
How is it going to blow if the positive terminal of the battery isn't connected to anything?
You've got a great point there ..............
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#### Ya’akov

Joined Jan 27, 2019
7,050
I understand you need to have a path to ground for something to work and now understand roughly the flow of electrons. My question is when you do not connect to ground, is there no flow at all. No leakage from the valid flow which is connected to ground. Sound silly as I don't need to understand just follow the rules but cannot help wondering.

I think you need to back up a bit.​

"I understand you need to have a path to ground for something to work"​

You don't understand, so you need to get the fundamentals right. In a very high level overview that will serve only as a start, here's a way to begin to think about it.​
Let's restrict the first look to chemical cells (batteries) because they offer a simplifiable view of the system. (A battery is a collection of cells, but the two words are interchanged in informal usage. It helps to keep the two to their technical meanings in contexts like this one.)​
In a chemical battery you have materials arranged so that two materials have an imbalance of electrons, and as a result, an electric charge that exists as potential between the two materials.​
The potential is measured in V (volts), and is the strength of the tendency of the electric charge to want to balance itself out between the two materials.​
One of the materials will have a surplus of electrons. Electrons carry a negative charge, so the material with the extra electrons is connected to the cathode (the negative terminal) of the cell. The other, having lost electrons will have a positive charge and be connected to the anode (positive terminal).​
 Let's step back for just a moment and clear up the idea of a "surplus of electrons". To have a surplus implies that you can have a deficit as well—which you can—but that necessarily means there must be a "just right" number. There is. Every molecule has two sorts of charged particles: electrons and protons. As we've said, the electrons have a negative charge, and they form a cloud outside the nucleus which is made up of particles including the proton which has a positive charge. In the "normal" state, the molecule's electrons and protons balance each other's charge resulting in a net zero charge overall. But electrons can be stripped away from the molecules which results in a positive charge for the donor and a negative one for the recipient. This state of affairs in unstable and at the first chance the positively charged material will happily and aggressively accept electrons to make up the deficit. In the case of our cell, the donor and recipient remain nearby with electrical connecting points for practical use.
To make use of the chemical energy stored in the cell as electric current, that is the flow of charge we used to power things, we connect a conductor between the cathode and anode. The flow of current can be understood in two ways, the one we will use is conventional current where it travels from the positive terminal through the circuit to the negative terminal.​
This view is completely useful but also wrong in particular ways. But it is a convention that literally started with a 50/50 chance Ben Franklin had to get it right, but didn't. For our purposes it doesn't matter as long as it stays consistent—in the end the results will the same.​
 As an aside, Franklin was also the person who named "batteries". A battery is a collection of cells, and in Franklin's day it would be a collection of glass jars. Each cell has an OTV (Open Terminal Voltage) depending on its chemistry, for example conventional manganese alkaline batteries have an OTV of about 1.5V and PbSo4 (Lead Acid) batteries measure at about 2V. Making the cell larger increases its capacity, that is, the total amount of energy it will store but not its OTV. So batteries cab be used to increase voltage by wiring them together in series (in parallel it adds their capacities as if it is a bigger cell, practical batteries often use both strategies to raise voltage and capacity at the same time). Franklin saw the collection of cells as reminiscent of artillery batteries which increased firepower by using a collection of canon, so that's what we have batteries and why one cell is not really a battery but it's a completely normal and accepted usage to call it that.
So, here we have the idea of a circuit, with current flowing through a conductor from one terminal to the other. The current flows because of the potential caused by the imbalance of electrons. The intensity of the potential is measured in volts.​
Note that there is no mention of "ground" here, just the closed loop from one terminal to the other, a path for the potential to cause current that equalizes the potential eventually and results in a "dead" or "flat" cell.​
All of the relationships among the potential (voltage, V or sometimes E as in energy but still measured in volts.), current (amperes, amps, A, or I), and the difficulty of moving charge through the circuit called resistance (ohms, Ω) are described Ohm's Law which says:​
$E = {I \times R} \\ \therefore\\I = {E \over R}\\\therefore \\R={E \over I}$​
Ohm's Law can really clear things up if you spend a little time learning it.
In a nutshell, current is proportional to voltage and voltage is inversely proportional to resistance. So, now we can define the conductor that makes up our circuit by saying it has a resistance low enough that the voltage applied can produce current.​
The higher the voltage the less the resistance will be able to do to stop current flow, even to the point where the air itself will conduct, so the circuit requires no wires or help, it just happens.​
Practical circuits include a load, that is a thing the electrical power will act on to do something useful. The load will have its own resistance, and the lower the resistance, the more current flow, the shorter the cell life.​
There is so much more, but I will leave you with one last thing. Practical cells will behave in accordance with Ohm's Law to a point. Cells have limits on their current producing capacity and once that is reached just calculating that more current should be flowing based on voltage and resistance won't make it so.​
But secretly, the cell is 100% compliant with the law. If you measure the voltage of the cell, you will find as the current drops so does the voltage. This voltage sag is necessary because if the cell could continue to produce the expected voltage nothing could stop it from producing the same current.​
The thing that drops the voltage and limits the current is called the ESR (Equivalent Series Resistance) of the cell. That is, if we look at the cell as if it were a resistor, how many Ω are we going to measure? This is generally quite a low number but as the current increases it becomes more and more significant. Play around with the equations to get a feel for it.​
So, the reason it's called Ohm's Law is that you can't violate it. It will always hold true, and if you think you found a loophole, you are missing something, probably a hidden resistance.​
There are a lot of resources to learn more, but you can also ask specific questions here and many people will be happy to help, Some one is sure to have a way of presenting the information that is simpatico with your brain.​
I look forward to more questions as you come up with them.​

#### dl324

Joined Mar 30, 2015
15,511
I understand you need to have a path to ground for something to work and now understand roughly the flow of electrons. My question is when you do not connect to ground, is there no flow at all.
There is no way for current to flow in your circuit.

The node you've labeled 5V (on the cathode of the LED on the left) is incorrect. You've defined that node to be earth ground.

In the circuits below, circuit ground has no relationship to earth ground.

Joined Jul 18, 2013
26,706
Its unfortunate that the term Ground has been misused time after time so that it has totally obscured the original meaning of referring to earth GND.
I never use to describe anything other than Earth, there are many other options, 'Common' is one.

As Dr Bruce Archambeault said it!

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#### bibble235

Joined May 29, 2018
54
I wasn't really asking about the circuit in question but about wires dead ended and did current stray regardless of the other end. I guess more of a physics question than electronics. But thanks all.

#### WBahn

Joined Mar 31, 2012
28,192
I wasn't really asking about the circuit in question but about wires dead ended and did current stray regardless of the other end. I guess more of a physics question than electronics. But thanks all.

If you go there, let me know if the equations rendered properly. They look fine when I use the Preview mode, but as near as I can tell, all of the equations appear as just text with $$and$$ replacing the tex tags.

#### Jony130

Joined Feb 17, 2009
5,440
If you go there, let me know if the equations rendered properly
No, they do not render properly.

#### MisterBill2

Joined Jan 23, 2018
14,280
"Ground" is a mythical concept that has zero resistance and zero potential and develops zero voltage across any segment no matter what current flows. It is often used as a substitute for "common", which is often correct for a circuit reference point used for voltage measurement or reference. So the easy to draw symbols for "ground" are in fact indications of connections to a specific common portion of the circuit that takes more effort to draw.
This includes the references to power distribution system common lines, which are usually tied to a fair approximation of "ground".

Joined Jul 18, 2013
26,706
It is often used as a substitute for "common", which is often correct for a circuit reference point used for voltage measurement or reference. So the easy to draw symbols for "ground" are in fact indications of connections to a specific common portion of the circuit that takes more effort to draw.
The terms 'ground' 'common' as well as the earth ground symbol are repeatedly misused, often by many that should know better, e.g. the often quoted, pub: "Art Of Electronics" show it wrongly throughout .
Where I originated from, we would use the more definitive term Earth, as in 'run power and an earth (conductor)'
For one definitive reference, there is Soares Book on Grounding, which is used by NFPA70 (NEC) as a reference, published by the International Assoc. of Electrical Inspectors.

#### WBahn

Joined Mar 31, 2012
28,192
The terms 'ground' 'common' as well as the earth ground symbol are repeatedly misused, often by many that should know better, e.g. the often quoted, pub: "Art Of Electronics" show it wrongly throughout .
Where I originated from, we would use the more definitive term Earth, as in 'run power and an earth (conductor)'
For one definitive reference, there is Soares Book on Grounding, which is used by NFPA70 (NEC) as a reference, published by the International Assoc. of Electrical Inspectors.
While I agree that they are misused, and this is very unfortunate, the fact remains that people (that many know better) still have to communicate with people (that may not). In most cases, the intent of the use is very obvious and clear. Even if someone wanted to insist that everyone they interact with get on board with the proper usage, there are far too many situations in which, because of the tools in use, they can't. For instance, some simulation packages use the earth ground symbol as the only means to tie a signal to the Node 0 reference. Then, of course, there are the countless data sheets that use them incorrectly. The simple fact is that people that work with power systems operate in a different world than people that work with battery-powered gadgets, and so the vocabularies used by each are not perfectly aligned. The same is true in many, many fields, and often in much more insidious ways.

Joined Jul 18, 2013
26,706
For instance, some simulation packages use the earth ground symbol as the only means to tie a signal to the Node 0 reference. Then, of course, there are the countless data sheets that use them incorrectly.
Then would not this be a gross mistake by whoever wrote the simulation S/W?
To me, there is no point in setting a standard, then many just ignoring it or not bothering to learn the correct way.
If a 'Standard' is not observed, It essentially renders it essentially useless.
I would think it is imperative that those that wish to operate within a certain discipline would be required to learn the standards set in said discipline.
Those such as Horowitz and Hill, who both have academic backgrounds in Electronics should know better?

#### WBahn

Joined Mar 31, 2012
28,192
Then would not this be a gross mistake by whoever wrote the simulation S/W?
To me, there is no point in setting a standard, then many just ignoring it or not bothering to learn the correct way.
If a 'Standard' is not observed, It essentially renders it essentially useless.
I would think it is imperative that those that wish to operate within a certain discipline would be required to learn the standards set in said discipline.
Those such as Horowitz and Hill, who both have academic backgrounds in Electronics should know better?
At the end of the day, it doesn't matter what should be nearly as much as it matters what is.

Those with only academic backgrounds are usually in the worst position to know better -- they have lived their lives insulated from the real world. To many of them, the distinction between circuit common, a chassis connection, a neutral conductor, and an earth ground is little more than semantics. I have no idea about Horowitz or Hill (I have their text, but have not found it particularly valuable), but I have known and interacted with a number of textbook authors in a few fields and most of them lack any meaningful actual experience beyond whatever contrived labs they did as an undergraduate. I've worked with any number of senior design teams whose advisors were completely ignorant of the need to provide anti-kickback protection on switched inductive loads or that the use of bypass capacitors at all, let along proper bypassing, was actually pretty important.

Don't get me wrong -- I sympathize with your struggle. I try to use and inject the correct terminology into discussions where I can, but there's a point where I'm not going to spend a whole bunch of effort to address the terminology when the person I'm talking to is just asking if they can use the junction of two 9 V batteries connected in series as their circuit ground. It's a hill I'm willing to do battle on, but not willing to die on. I save that for other hills, like properly tracking units.

Joined Jul 18, 2013
26,706
Don't get me wrong -- I sympathize with your struggle.
It's just another pet-peeve!

#### LowQCab

Joined Nov 6, 2012
2,940
I look at it the same way that I look at peoples use of Speech/Language/Pronunciation of Words.
People learn a particular dialect and/or group of Colloquialisms, and/or Speech-Patterns,
that are sometimes partially incorrect, or even grossly incorrect,
but they're apparently stuck with it,
and have been doing it that way for most, if not all, of their lives.

You can find it entertaining, and a challenge, or
You can try to make yourself feel superior to others by
making them appear to be somehow less than You.

As long as the intention can be reliably gleaned, then "it's all good".
Variety is the Spice of Life.
The best You can do to help others is to set such a good example,
that others will want to adopt it for themselves.

Maybe one day we'll have Educational-Systems that actually
teach people HOW TO LEARN and why You would want to Learn.

But, of course, if everybody was the same, Life would be hopelessly boring.
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#### MisterBill2

Joined Jan 23, 2018
14,280
Returning to the original question, in a low voltage DC circuit no current flows from an open circuited wire. Consider that the word "circuit" is what the line in a circle describes. In a low voltage DC system there must be a complete conductive path for a current to flow.
By "low voltage" I mean a voltage not high enough to ionize the atmosphere around the wire, which is a HIGH voltage by any standard. By DC I mean a fairly constant potential that does not vary rapidly enough to charge and discharge the capacitance to nearby conductive objects.
There are many books available that describe DC circuit theory well enough to answer the questions that arise, and slightly old college textbooks can be a very inexpensive source. DC circuit theory does not change and so the older texts are still correct.