Ohm's Law & Non-Linear Circuits

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Discussion Overview

The discussion revolves around the applicability of Ohm's Law in the context of non-linear circuits, exploring the limitations and modeling approaches for non-ideal systems. Participants examine the relevance of linear models in practical scenarios where non-linear behaviors are present.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant asserts that Ohm's Law is only applicable to linear circuits and questions its utility given that many real-world loads are non-linear.
  • Another participant draws parallels with other laws, suggesting that all models have limitations and questioning the value of those laws in practical applications.
  • A participant proposes that non-ideal systems can be modeled ideally while neglecting small errors, implying a trade-off between accuracy and practicality.
  • One participant challenges the notion that most loads are non-linear, arguing that many loads are resistive and that linear elements can still be analyzed in complex circuits.
  • Another participant suggests a staged approach to modeling non-linear circuits, utilizing linear analysis for initial states and applying Laplace transform theory for transient signals, emphasizing the importance of accurate component specifications.

Areas of Agreement / Disagreement

Participants express differing views on the prevalence of non-linear loads and the applicability of Ohm's Law, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

Limitations include assumptions about the linearity of components, the accuracy of models used in simulations, and the dependency on precise specifications for circuit analysis.

derek181
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Ohm's law only applies to linear circuits. If most loads in life are non-linear, what use is ohm's law?
 
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Hooke's Law is only good for perfectly elastic and massless springs. What use is it?
PV=nRT is only good for ideal gasses, of which there are none. What use is it?

Get the idea?
 
So we model non ideal systems in an idea way and neglect the small error?
 
Why do you think most loads are non-linear? Most loads are largely resistive. Even when the output of a circuit is driving a complex impedance there are plenty of linear elements to analyze in there.
 
You can model the non-linear circuit by taking it in stages: the switch is open (mechanical or transistor) - now carry out a linear analysis. The switch closes - use Laplace transform theory to find the transient signal.

This plus the final state of the previous analysis (states of capacitors and inductors) allows your to carry out an analysis of the next stage. Repeat ad nauseum. This is what a good Spice program does. The limitations are based on the models for the individual properties of the components being used - wrong specs, wrong results.

Oh - and if you want perfection, then you must know the lengths of wires, the resistivity, and the qualities of all of the connections, soldered and unsoldered.
 

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