Putting a ground in between circuit

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Discussion Overview

The discussion centers around the implications of placing a ground connection between two resistors in a series circuit. Participants explore the behavior of current in relation to grounding, circuit paths, and the conditions under which current flows through different components. The scope includes theoretical considerations and practical implications in circuit design.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant questions whether current will flow through the ground wire instead of the second resistor when a ground is placed between two resistors in series.
  • Another participant asserts that current will not flow through the ground unless one side of the battery is also grounded, emphasizing that ground serves as a reference point in the circuit.
  • A participant proposes that if the ground is connected to the negative terminal of the battery, then current would flow through the ground wire.
  • There is a quiz question posed regarding why current does not flow towards the ground in the given circuit configuration.
  • Responses indicate that a single Earth ground connection does not affect a floating circuit, while multiple connections can create parallel paths for current.
  • One participant asks for a theoretical explanation of why an electron would prefer to stay within the loop of the circuit rather than travel towards the ground.
  • Another participant explains that with only one ground connection, the voltage at that point is 0V, and current requires a loop to flow, which is not present in the described configuration.
  • Concerns are raised about the idealization of zero-resistance paths and how they relate to current flow in practical circuits.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of current in relation to grounding, with no consensus reached on the implications of grounding in the circuit configuration discussed. The discussion remains unresolved regarding the quiz question and the theoretical explanations sought.

Contextual Notes

Participants note the importance of understanding the circuit configuration, including the role of grounding and the necessity for current to flow in loops. Limitations in the discussion include assumptions about the circuit's grounding and the implications of ideal versus real-world conditions.

salman213
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[SOLVED] Putting a ground in between circuit

If i put a ground in between the two resisters that are in series of a circuit, will the current go through the ground wire and NOT the 2nd resister. Example..

this is not a hwk question by the way. I just drew this right now on paint

http://img247.imageshack.us/img247/503/45634000nf9.jpg

I didnt have time to test this out in my circuits lab yesterday but i was wondering what it will do

A1 will have current measurement for sure

but A2 and A3

?:S? what will be the readings like will A3 even have a reading or not..
 
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No current will flow through A2 unless you also ground one of the sides of the battery.
I assume that IS a battery? if it is a generic voltage source than the result will depends on whether or not the negative terminal is connected to ground.

Ground is is REFERENCE POINT in a circuit, nothing more.
Current doesn't go to ground unless it can flow in a loop (e.g. flowing back to the negative terminal of a grounded source).
 
so if the ground was also connected to the negative terminal then all of the current would go through the ground wire?
 
No current will flow though the ground connection as you have drawn the circuit. Quiz question -- why not?

BTW, this is still coursework, so I'll move it to the Homework Help forum.
 
salman213 said:
so if the ground was also connected to the negative terminal then all of the current would go through the ground wire?

Yes if the negative terminal of the 'battery' was actually an earthed PSU then the current would flow through A2.
You also have to be careful when using an oscilloscope since the clips on the probes are earthed. It's a common question in electronics labs how to measure the signal through R1/R2 with a scope without shorting out the circuit.
 
none

Berkeman could you please answer the quiz? Is there a good theoretical or physical explanation why the current ''chooses'' not to travel towards the ground?
 
Ricky2357 said:
Berkeman could you please answer the quiz? Is there a good theoretical or physical explanation why the current ''chooses'' not to travel towards the ground?

mgb answered the Quiz Question with his post:

mgb_phys said:
Yes if the negative terminal of the 'battery' was actually an earthed PSU then the current would flow through A2.

A single Earth ground connection anywhere in a floating circuit does nothing. If you make more than one connection in the circuit to Earth ground, then that forms a parallel path for currents to flow.
 
Yes, I can understand why this is true. The quiz question has not been answered though. Imagine you are an electron in the circuit drawn above and as you travel you encounter two separate paths. One leads eventually to the ground while the other keeps you within the loop. Why do you choose the second?
Please correct me if my question is not well-posed. Thank you.
 
Ricky2357 said:
Yes, I can understand why this is true. The quiz question has not been answered though. Imagine you are an electron in the circuit drawn above and as you travel you encounter two separate paths. One leads eventually to the ground while the other keeps you within the loop. Why do you choose the second?
Please correct me if my question is not well-posed. Thank you.

Since there is only one Earth ground connection shown, call the voltage at that point 0V. The ammeters A1 and A2 are short circuits, so the points between A1, A2 and R2 and including that end of R1 on the other side of A1 are also at 0V (relative to Earth).

The battery imposes a voltage potential across R1 and R2, with 0V in between the two resistors. The absolute voltages on the battery side of R1 and R2 are determined by the battery voltage and the resistor divider ratio, again with 0V being forced in between the two resistors.

There is no "loop" to the Earth ground branch as drawn -- there is no return to another place in the circuit from Earth ground. Current has to flow in loops, so there is no loop for an electron to follow toward Earth ground when it is flowing between R1 and R2.
 
  • #10
So I see. No loop means no current. I guess what was puzzling me was the following statement:

''In theory, if current has a choice between a zero-resistance path and a finite resistance path, all the current takes the path of zero resistance; a path with zero resistance, however, is an idealization.''
 

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