Calculating Power Dissipation in a Circuit

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Discussion Overview

The discussion revolves around the calculation of power dissipation in a circuit involving a non-ideal battery with internal resistance. Participants explore whether to include internal resistance in power calculations and how to interpret questions regarding power supplied by the battery.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant questions whether to account for the internal resistance of a battery when calculating power dissipation, suggesting a method that excludes it.
  • Another participant argues that the power dissipated in the internal resistance contributes to the heating of the battery and is not available to the circuit, emphasizing that power in the circuit should be calculated based on the load current and voltage across the load.
  • A later reply clarifies that the interpretation of a question about power supplied by the battery should focus on the power drawn by the load, distinguishing it from internal dissipation.
  • Further clarification is provided that questions regarding total power expended by the battery would explicitly mention internal dissipation.

Areas of Agreement / Disagreement

Participants express differing views on whether internal resistance should be included in power calculations, indicating that multiple competing perspectives remain unresolved.

Contextual Notes

Participants do not reach a consensus on the interpretation of power calculations involving internal resistance, and assumptions about question phrasing are not fully explored.

JSGandora
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If I ran over a problem asking for power supplied by a non-ideal battery, or a battery with an internal resistance. Do I account for the internal resistance when I calculate the power dissipation? Or do I just account for the loads (finding the total resistance excluding the internal resistance of the battery and then multiplying it by the current squared to get the power) excluding the internal resistance?
 
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Surely that depends on the question?

The power dissipated in the internal series resistance is the reason batteries become warm/hot when you draw power from them.
But this power is unavailable to the circuit. The power in the circuit is the product of the load current and the voltage across the load.
 
Oh, I see now. Thanks for your clear response!
 
go well
 
Hmm? What do you mean by "go well"?

Also, just to make sure, if the questions stated "What is the power supplied by battery D?", then we only account for the power dissipated by the load, correct?
 
Go well is an English phrase wishing you good fortune in the future.

I would take the question
"What is the power supplied by battery D?"

To mean the power drawn by the load.

I think the key word is 'supplied'
The internal dissipation wasted in heating the battery is not supplied to anything.

I would expect a question including the internally dissipated power to read something like

'Find the total power expended by the battery' or 'Find the total power developed by the battery'.
 
Thank you, it's very clear to me now. Go well to you too!
 

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