What will be the total resistance of ideal voltage source?

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Discussion Overview

The discussion revolves around the total resistance of a circuit that includes an ideal voltage source and a resistor. Participants explore the implications of an ideal voltage source's characteristics on total resistance, considering both theoretical and practical aspects.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the total resistance of a circuit with an ideal voltage source and a resistor could be zero, questioning how a circuit can have a resistor yet exhibit zero total resistance.
  • Others argue that the internal resistance of an ideal voltage source is zero, implying that the total resistance remains zero regardless of the load connected.
  • A participant clarifies that the effective resistance of a circuit with an ideal voltage source in parallel with any load is zero ohms, but this raises questions about the definition of "total resistance."
  • One participant introduces the concept of Thevenin equivalent circuits, explaining that the total resistance can be calculated differently depending on whether the circuit is analyzed for DC or AC conditions.
  • Another participant emphasizes the need for clarity in the question posed, noting that the term "total resistance" must be defined and the configuration (series or parallel) specified for accurate measurement.

Areas of Agreement / Disagreement

Participants express differing views on the concept of total resistance in circuits involving ideal voltage sources, with no consensus reached on the definition or implications of total resistance in this context.

Contextual Notes

Limitations include the ambiguity in the term "total resistance" and the dependence on circuit configuration (series vs. parallel) when measuring resistance. The discussion also highlights the distinction between DC and AC analysis in circuit calculations.

Sampad Saha
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If we connect a single resistor in the circuit of ideal voltage source then what'll be its total resistance? ? Isn't it zero? As shown in image .so is it possible that the total resistance of a circuit is 0 Although it has 5ohm resistor!?
IMG_20150403_091252.jpg
 
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An ideal voltage source can power any load you throw at it while continuing to maintain a constant voltage. So its resistance remains zero.
 
NascentOxygen said:
An ideal voltage source can power any load you throw at it while continuing to maintain a constant voltage. So its resistance remains zero.
yaa..Sir, I know that its internal resistance must be zero. But what's about total resistance of the circuit? Is it also be zero?
 
If that wasn't the answer to your question, then you weren't asking the right question. The voltmeter is across the source, so regardless of what else is going on, its voltage is held fixed by that source.

The effective resistance of a circuit comprising an ideal voltage source in parallel with anything is zero ohms.
 
Sampad Saha said:
yaa..Sir, I know that its internal resistance must be zero. But what's about total resistance of the circuit? Is it also be zero?
I think maybe you are confused about the calculating the equivalent impedance (resistance in your case) of a circuit.
There are 2 circuits to draw.
The first circuit is the Thevenin equivalent of the circuit. In your case, it would be an ideal voltage source with a 0 Ohm series resistance. This circuit is used to calculate DC values mostly. So in this case if the voltage is 5 V and the load resistor is 5 Ohms, the DC current is 1 Amp.
The second circuit is the equivalent impedance (or resistance in your case) of the circuit. This circuit is calculated by replacing ideal voltage sources with a wire (I.e., shorted). In your case, this circuit becomes just a resistor of 0 Ohms (Note that there is no voltage source in this circuit). The 5 Ohm load is still across the terminals. Normally this circuit is used for AC analysis. Suppose you connect a 110 VAC supply with a 110 Ohm resistor in series across the 5 Ohm resistor. What is the AC voltage across the 5 Ohm resistor? By superposition, the voltage across the terminals is 5 Volts DC (calculated from the first circuit) plus 0 VAC (calculated from the second circuit). Normally the equivalent impedance is not zero and there is an AC component across the terminals. By using the equivalent circuit impedance, the task of calculating signal levels is made easier.
Hope this helps.
 
Sampad Saha said:
If we connect a single resistor in the circuit of ideal voltage source then what'll be its total resistance

A question well stated is half answered.
Above question is not well stated. You introduced a term that you did not first define.

Just what do you mean by "total resistance" ?
The "total" of all the resistances in your circuit is 5 ohms + Rvoltmeter.

Are you considering your voltage source and resistor as being in series or being in parallel when you measure "total resistance" ??

You must define between what two points you intend to measure said "total resistance" .
 

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