Putting a ground in between circuit

In summary: I was thinking that the ground wire would offer the electron an alternative (path of zero resistance) to the one through the 2 resistors (path of finite resistance).In summary, when there is only one ground connection in a circuit, it serves as a reference point and does not allow current to flow through it unless there is a complete loop. In the case of the given circuit, the current will flow through A1, but not through A2 or A3 unless there is a connection from the negative terminal of the battery to ground. In this scenario, the ground wire would offer a path of zero resistance, but since there is no complete loop, the current will still not flow through it.
  • #1
salman213
302
1
[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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  • #2
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).
 
  • #3
so if the ground was also connected to the negative terminal then all of the current would go through the ground wire?
 
  • #4
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.
 
  • #5
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.
 
  • #6
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?
 
  • #7
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.
 
  • #8
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.
 
  • #9
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.''
 

1. What is the purpose of putting a ground in between a circuit?

The purpose of putting a ground in between a circuit is to provide a safe path for excess electrical current to flow. This helps prevent damage to the circuit and any connected devices in case of a power surge or other electrical issue.

2. How does a ground in between a circuit work?

A ground in between a circuit works by connecting the circuit to the earth's surface, which acts as a large reservoir of charge. This allows excess electrical current to flow into the ground instead of building up in the circuit, thus preventing damage.

3. Can I use any material as a ground in between a circuit?

No, not all materials can be used as a ground in between a circuit. It is important to use a material that is able to conduct electricity, such as copper or aluminum, in order for the ground to effectively dissipate excess electrical current.

4. Is a ground in between a circuit necessary for all electronic devices?

Yes, a ground in between a circuit is necessary for most electronic devices. It is especially important for devices that have metal components or are connected to other metal objects, as these are more susceptible to power surges and electrical issues.

5. How do I know if a ground in between a circuit is working properly?

To ensure that a ground in between a circuit is working properly, you can use a multimeter to check for continuity between the ground connection and the earth's surface. You can also hire a professional electrician to inspect the circuit and make sure it is properly grounded.

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