Can Charge Flow in an Open Circuit?

In summary: Presumably what's happening is that the potential difference between the wires is creating an electrostatic field, and the electrons on the negative wire are being drawn to the positive wire.In summary, a Leyden jar is a capacitor where the potential difference between the plates creates an electrostatic field, and the electrons on the negative wire are drawn to the positive wire. This is how charge can flow without a return path.
  • #1
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I've always wondered why is it possible for charge to flow in an open circuit, e.g., when a terminal is connected to a grounded pole, a large metal chassis, or say a water pipe.

I've assumed that it's because there is a positive potential difference between where the charge is and the large conductive body, and so its potential energy is dissipated in moving towards the conductive body which thus creates current.

The circuit can remain open, with no return path, since there is no charge buildup as there would be on say a parallel plate capacitor.

Are these thoughts correct? Any further insight into the matter? I noticed that it seems that this is how Leyden Jars were originally charged, the outer foil on the jar had no return path. Please let me know if I'm wrong regarding this as well.
 
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  • #2
Current doesn't flow without a path
It's just that sometimes the path isn't obvious.
There is a path through the Earth from a grounded pole, on a Leyden jar there is a path across the glass or through the air.
 
  • #3
The Layden Jar is a capacitor.

The grounded circuits don't work without a return path. If you are using a battery as a voltage source, the reaction inside the battery cannot occur unless there is charge balance in the electrochemica reaction.

If you are using a change in magnetic flux as your emf, then the wire cannot simply give away charges without getting the charge back. Okay, maybe a few electrons can get out but the coulombic attraction will become large very quickly, and the wire will stay approximatelly neutral.
 
  • #4
Well how would we explain say lightning, where is no apparent return loop? Or when a circuit is grounded to Earth in case of an overabundance of current, and the charge will indeed travel to the ground. There doesn't seem to be a return loop in either example, and it seems that what makes both events occur is the high potential difference and the presence conductor on the other side.

Regarding a Leyden jar: it is seemingly charged without a return loop, that is the capacitor's plates are not put across a battery. The original jar was connected to an electrostatic generator at the top and then charged by it, hence current temporarily existed (within its RC time constant I imagine) before the capacitor was charged. Again, how can charge ever flow without a return path?

This, IMO, http://www.wonderhowto.com/how-to-build-leyden-jar-and-use-capacitor-272817/" regarding capacitors also made me question this. You can watch the video, or fast forward until ~3:50 for the construction of a miniature Leyden Jar, and at ~4:37 he comments that he will connect the red wire to a faucet.

There is no way that charge is returning to the yellow wire in the video as it would have to traverse relatively enormous quantities of air, and arcing would be very visible.
 
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  • #5


Your thoughts are correct. In an open circuit, the flow of charge is possible because of the presence of a potential difference between two points. This potential difference can be created by connecting one terminal of a battery to a conductive body, such as a grounded pole or a large metal chassis, as you mentioned. This creates a difference in the electric potential between the two points, and charges will flow from the higher potential point to the lower potential point until the potential difference is equalized.

In the case of a Leyden Jar, the outer foil acts as one terminal, while the inner foil acts as the other terminal. When the jar is connected to a conductive body, such as a grounded pole, the potential difference between the two foils is created, and charges will flow from one foil to the other until the potential difference is equalized.

It is important to note that in an open circuit, the flow of charge is not sustained, as there is no closed loop for the charges to continuously flow through. Once the potential difference is equalized, the flow of charge will stop.

In summary, the flow of charge in an open circuit is possible due to the presence of a potential difference between two points, and it is not sustained as there is no closed loop for the charges to continuously flow through.
 

What is an open circuit?

An open circuit is a circuit that does not have a complete path for the current to flow. This means there is a break in the circuit and the current cannot flow through it.

How does current flow in an open circuit?

In an open circuit, there is no continuous path for the current to flow. Therefore, the current cannot flow and there is no movement of electrons. This is why an open circuit is considered to be an incomplete circuit.

What is the effect of an open circuit?

An open circuit has the effect of interrupting the flow of current. This means that any devices or components connected to the open circuit will not receive the necessary current to function.

How is an open circuit different from a closed circuit?

A closed circuit is a complete and continuous path for the current to flow, while an open circuit is an incomplete path with a break where the current cannot flow. In a closed circuit, the current can flow and power devices, while in an open circuit, the current cannot flow and the devices will not function.

What can cause an open circuit?

An open circuit can be caused by a variety of factors, such as a broken wire, a loose connection, a blown fuse, or a malfunctioning component. It is important to check all components and connections to identify the cause of the open circuit.

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