Current in Open Circuits

• dancergirlie
In summary, the conversation discusses an open circuit demonstrated in figure 2 and determines the current and voltage at point p. It is concluded that with no connection, the resistance would be infinite and the current would be zero, resulting in a voltage of 12V across the battery. The actual battery voltage specified in the problem is 5V.

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?

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
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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!

1. What is an open circuit?

An open circuit is a type of electrical circuit in which there is a break or interruption in the flow of current. This can be caused by a switch being turned off or a wire being disconnected.

2. How does current flow in an open circuit?

In an open circuit, there is no complete path for the current to flow. As a result, the current stops flowing and there is no transfer of energy. The circuit remains incomplete until the connection is reestablished.

3. What happens to the voltage in an open circuit?

In an open circuit, the voltage remains the same throughout the circuit. This is because there is no current flowing to cause a change in voltage. The voltage will only change if the circuit is closed and current is able to flow.

4. How can you measure current in an open circuit?

In an open circuit, there is no current flowing. Therefore, it is not possible to measure the current using a traditional ammeter. However, you can measure the voltage across the open circuit using a voltmeter to determine if there is a break in the circuit.

5. What are some examples of open circuits?

Some examples of open circuits include a light switch being turned off, a broken wire in a string of holiday lights, or a disconnected battery in a flashlight. In each case, the circuit is open and current is unable to flow.