Analyzing Open Circuits: Current and Voltage

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Homework Help Overview

The discussion revolves around an open circuit scenario, specifically analyzing the current through an ammeter and the voltage at a certain point in the circuit. Participants are considering the implications of an open circuit on current and voltage measurements.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the relationship between open circuits, current, and voltage, with some suggesting that current should be zero and others exploring the implications of resistance in the context of Ohm's law.

Discussion Status

The discussion is active, with various interpretations being explored regarding the behavior of voltage and current in an open circuit. Some participants have offered insights into the implications of resistance and potential differences, while others express uncertainty about their reasoning.

Contextual Notes

There is mention of specific battery voltages and the assumption that the circuit is open, which influences the discussion on current and voltage measurements. Participants are also considering the implications of infinite resistance in their reasoning.

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Homework Statement



Looking at the open circuit demonstrated in figure 2 (see attachment), what is the current through the ammeter? What is the voltage at point p?

Homework Equations





The Attempt at a Solution



I am assuming if it an open circuit, I would think that the current would be zero (I might be wrong though). Meaning that since the current is zero, so is the voltage.

I have a feeling I might be wrong though...

Any help would be great!
 

Attachments

  • Screen shot 2011-01-24 at 11.10.07 PM.png
    Screen shot 2011-01-24 at 11.10.07 PM.png
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What's the voltage across the terminals of a 12V battery that's not connected to a circuit? What current is it producing?
 
Wouldn't the voltage be 12V? However there is no resistance, so using ohm's law: I=V/R, with 0 resistance, that would make the current infinite, which doesn't make any sense...
 
dancergirlie said:
Wouldn't the voltage be 12V? However there is no resistance, so using ohm's law: I=V/R, with 0 resistance, that would make the current infinite, which doesn't make any sense...

With no connection the resistance would be infinite; no conductivity.

So in your circuit, what's the total resistance between the battery terminals?
 
Well since it is not connected then it would be infinity

Using my Ohm's law argument that would give us our voltage of 12 volts across the battery

and 12/inf is approx 0, so the current would read out zero.

Am I right? If so then thank you so much!
 
Right; The open circuit dangling off of the positive battery terminal would all be at the battery's potential, and no current would be flowing. By the way, I chose 12V as an example. Check the actual battery voltage specified in your problem.
 
Yeah I noticed that, mine would be 5V :)

Thank you so much, that makes total sense!
 

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