Grounding in electrical circuits

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Discussion Overview

The discussion revolves around the concept of grounding in electrical circuits, contrasting it with grounding in mains power. Participants explore the purpose of ground in circuits, its necessity, and the implications of different grounding practices.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants express confusion about the distinction between circuit grounding and mains grounding, questioning the necessity and function of ground in circuits.
  • One participant notes that voltage is a differential quantity, requiring a reference point, often referred to as "ground," which may not be physically connected to Earth.
  • Another participant describes a scenario involving multiple power supplies, suggesting that the negative terminal can serve as a common reference point for measuring voltage across components.
  • There is a discussion about the concept of floating grounds, where the ground reference may not be connected to Earth or another circuit.
  • Some participants highlight that the term "ground" can refer to circuit common or a zero voltage reference, depending on the context.
  • A later reply emphasizes that voltage is relative, and establishing a ground allows for the use of absolute voltage language.
  • One participant introduces the idea of virtual or artificial grounds, suggesting that these can have current flow and still satisfy certain definitions of ground.
  • Another participant uses a flashlight battery analogy to illustrate that a circuit can function without a connection to Earth ground, emphasizing that current flows back to the battery rather than to Earth.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the definitions and implications of grounding, with multiple competing views and ongoing questions about the nature and necessity of ground in various contexts.

Contextual Notes

Some discussions involve assumptions about the physical connections of grounds, the definitions of terms like "circuit common," and the implications of grounding practices in different applications.

  • #61
@Jim

That's a fair enough view but it doesn't really constitute Physics imho. You don't need Physics to fix your car electrics, usually, but there are a number of problems I have solved which have benefited a lot from something more than the 'complete circuit' idea.
This is supposed to be a Physics Forum - not a car fixit helpline. I think it only reasonable that people who present problems, based on Physics, should expect answers which are at least a bit demanding.

Is it showing off to tell people that they need to do more than first year Science and they will need some reasonable Maths if they are going to get a better understanding? Is it showing off to tell people that they will not be able to run a Marathon without some serious training? Or that they will need to learn to swim before they jump into the deep end of the pool?

Inverted snobbery never got anyone anywhere.

I agree that the New Math approach didn't work - but that isn't really a parallel. The 'why' is essential when you want to do more than arithmetic. There are very few valid arm waving 'explanations' to help someone perform a Fourier Transform or Correlation.
 
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  • #62
Studiot said:
Gosh I must remember that little aphorism - it applies so well to other disciplines as well as maths.

:wink:

"just sodding learn it. Then we can discuss it."
That gets my vote every time!
 
  • #63
"""I think it only reasonable that people who present problems, based on Physics, should expect answers which are at least a bit demanding."""

Fair enough.



old jim
 
  • #64
jim hardy said:
Does this mean that our current just changed?""

no, it just means the electrons are(or should we say charge is) are packed a little closer together inside the wire.
current will flow in accordance with Ohm's law just as it did before the strike.

Thank you Jim... This makes sense to me now. I can see now how we can have a complete circuit and still have a potential to ground. I never really thought of it that way until you made this statement.

I appreciate your way of explaining things... It is quite helpful to some of us.

On a side note... I think it is unwise to dismiss the importance of a complete circuit, especially when the discussion revolves around grounding. It is surprising to me how many people think that electricity wants to flow into the earth. This thread hits on the heart of the matter where "circuit electricity" blends with "static electricity". While some may think this is a trivial thing, it is widely misunderstood in my experience.

Thank you to all who have contributed to this. I hope this thread has helped people to have a better understanding of the concept. It has definitely helped me...

As Studiot would say... Go well
 
  • #65
"a complete circuit" is not 'dismissable'. It's just the first step in getting to grips with electronics - and no more.
 
  • #66
Evil Bunny said:
Thank you Jim... This makes sense to me now. I can see now how we can have a complete circuit and still have a potential to ground. I never really thought of it that way until you made this statement.

I appreciate your way of explaining things... It is quite helpful to some of us.

....

Thank you to all who have contributed to this. I hope this thread has helped people to have a better understanding of the concept. It has definitely helped me...

As Studiot would say... Go well

Thank you EB for your kind, kind words.
I believe we need simple models to get our thinking in order.part of a good education is an awareness of just how meager our knowledge really is.

i think so long as we keep in mind that every step in our learning process invites another , we'll be okay. It's dangerous to think we have arrived at some summit of knowledge. At least for me, it always results in some humbling event.
I once read in an erudite journal a statement to this effect:
"Electrical energy does not flow along wires, it flows in the electric and magnetic field surrounding them."
Now THERE was a corker, for the electrons-in-motion (oops charge-barely-in-motion) model that i grew up with doesn't look outside the wire at all.

But it helps people resolve apparent logical conflicts like you described.

So - keep on refining your mental models of how things work.
Maybe you'll explain to me about that energy being in the field along the wire...

old jim
 

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