How can Thevenin equivalent circuits be represented using a mechanical analogy?

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Discussion Overview

The discussion revolves around the representation of Thevenin equivalent circuits using mechanical analogies, particularly from the perspective of mechanical engineering students. Participants explore how concepts from mechanics can be applied to understand electrical circuits, focusing on analogies between forces, pressures, and electrical quantities.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses difficulty in understanding Thevenin equivalents and suggests that a mechanical analogy might be more accessible.
  • Another participant proposes a specific electrical/mechanical analogy where currents correspond to forces, voltages to velocities, resistances to viscous friction, capacitances to masses, and inductances to the inverses of spring constants.
  • A detailed analogy is presented involving two types of pumps and pipe systems, suggesting that different configurations can yield identical pressure and flow rates, paralleling Thevenin equivalents.
  • One participant acknowledges confusion but shows some understanding of the mechanical analogy concept.
  • A request for clarification on specific difficulties with Thevenin equivalents is made, indicating a desire for deeper understanding.
  • A later reply discusses the analogy of an I-beam in a skyscraper, suggesting that complex systems can be simplified to single forces and shears, similar to how resistors in a circuit can be reduced to a Thevenin equivalent.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding Thevenin equivalents and the mechanical analogy. While some find the analogy helpful, others remain confused, indicating that the discussion does not reach a consensus on clarity or correctness of the analogies presented.

Contextual Notes

Some participants note that the mechanical analogy may not be physically correct, highlighting the limitations of the analogy in accurately representing electrical concepts.

Who May Find This Useful

Mechanical engineering students, electrical engineering students, and individuals interested in interdisciplinary approaches to understanding circuit theory may find this discussion relevant.

morry
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My lecturer mentioned something about how you can represent Thevenin equivalent circuits with forces etc. As a mech eng student, this would be easier to understand than stupid resistors and voltages. :)

Does anyone know what I am on about? I can't think of how you could do this, but then again, I don't really understand Thevenin all too well.

Cheers.
 
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In making an electrical/mechanical analogy, you can replace currents by forces, voltages by velocities, resistances by viscous friction (the friction force is proportional to speed), capacitances by masses and inductances by the inverses of spring constants.
Does it help?
 
A) A pump which holds a constant pressure at the head and can deliver infinite
flow is connected to a flowmeter via a section of finite diameter pipe.

B) A second pump which maintains a constant flow rate and can develop any
pressure at the head is connected to itself with another short pipe section.
A pressure gauge measures the pressure at across this pipe.

For any type of pump and pipe section in situation A, you can find another
pipe and pump of type B that will have an identical pressure and flow
rate for any type of a second branch pipe you may connect to either
A or B. You won't know from measuring the flow and pressure at the service
pipe whether you are geting your fluid from a type A or type B system.
 
Hmm, I am still a bit confused, but I kinda get it. Thanks guys.
 
What exactly are you having trouble with in understanding Thevenin equivalent circuits?
 
re

This mechanical analogy may not be physically correct, but the idea is the same.

Suppose you pick any I-beam in a skyscraper, and want to analyze all forces, shears and stresses that are acting on it. If you could reduce all that junk to a single force and shear you could model what's going to the I-beam.

Similarly with resistors (I-Beam)

Suppose you have a glob of interconnected resistors with voltage and current sources. If you pick any resistor in the circuit, you can model what's going on between the two nodes across you resistor with a single voltage source (thevenin) and another resistor (thevenin).

If you then take your resistor that you picked and connect it to the thevenin voltage source and the thevenin resistor, it will give you the same effect if your resistor was connected to whole circuit.
 
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