Voltage Source with output of OV

In summary: WarrenIn summary, the conversation revolves around the effects of a voltage source being turned off or outputting a very low voltage. It is mentioned that an ideal voltage source set for 0V would act as a short, but a real voltage source with internal components may not. Additionally, connecting a powered down voltage source to two points with the same potential difference would not result in any current flow. The conversation also touches on the superposition theorem and the difference between an ideal and real voltage source.
  • #1
flexifirm
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My friend asked me a question that totally shocked me for a second.. here was the question...

"Is a voltage source turned off the same as a voltage source outputting 0V or near 0V?"


Then he asked me if we connected the two terminals of a voltage source to two points on an already ENERGIZED dc network... and the voltage output of the voltage source matches the exact same voltage that was in the network between the two points.. what is the effect? What is the effect when we change the voltage source (variable) to an output of 0.000001V and plug it between those two points? WHat is the effect of turning off the voltage source and plugging it between those two points?


My take on it is... a voltage source turned on but outputting 0V should be considered a short, but turned off should be considered an open (I'm thinking back to a simple power supply with a bridge rectifier a cap and a zener... u have the bridge to provide the open - yet in one direction current can go in one terminal of the power supply... through a set of diodes and come out the other end of the supply).

Also, when using the superposition theorem.. we TURN OFF the sources... and we replace an ideal voltage source with a short...


Any thoughts on what my inquisitive friend was blabbering about?
 
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  • #2
A voltage source does not "output" a voltage -- it maintains a voltage between its terminals by sourcing current, if necessary. An "ideal" voltage source set for 0V would indeed act as a short. A real voltage source, however, is quite complicated inside, with transistors and capacitors and other internal components; turning it off probably won't make it into a short.

If you connect a 5V source to two wires already having a potential difference of 5V, nothing "happens," in the sense that no current flows.

- Warren
 
  • #3
"Is a voltage source turned off the same as a voltage source outputting 0V or near 0V?"

If your voltage source is powered down, then the output might not be shorted.

Regards
 

1. What is a voltage source with an output of 0V?

A voltage source with an output of 0V is a device that provides a constant potential difference or voltage between its two terminals, but the voltage output is zero. This means that there is no flow of electrical current in the circuit, and the voltage source is essentially "off".

2. How does a voltage source with an output of 0V work?

A voltage source with an output of 0V works by maintaining a constant potential difference between its two terminals, even though the voltage output is zero. This is achieved by balancing the internal resistance of the voltage source with an equal and opposite resistance in the circuit, resulting in a net voltage of 0V.

3. What are the applications of a voltage source with an output of 0V?

A voltage source with an output of 0V is commonly used in electronic circuits as a reference voltage for measurement purposes. It can also be used as a starting point for voltage divider circuits or as a power supply for low voltage devices.

4. Can a voltage source with an output of 0V be used as a power source?

No, a voltage source with an output of 0V cannot be used as a power source as it does not provide any electrical current. It only maintains a constant potential difference, but without any flow of current, it cannot power any devices.

5. How is a voltage source with an output of 0V different from a short circuit?

A voltage source with an output of 0V and a short circuit are two different concepts. A short circuit is a connection between two points in a circuit with very low resistance, allowing a large amount of electrical current to flow. On the other hand, a voltage source with an output of 0V has a high internal resistance, resulting in no flow of current in the circuit.

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