# Effective resistance for Thevenin's theorem

• irrationally
In summary, the conversation discusses finding the effective Thevenin's resistance between two points in a circuit and how it can be calculated. The concept of effective resistance between two points is explained, and the confusion over whether to include a "hanging edge" in the calculation is addressed. The importance of clarifying any doubts is emphasized.

## Homework Statement

Me again. I again got confused with 2 similar things done differently on two different places. Let's say we have some arbitrary circuit and we want to replace a part of it with thevenin's generator. We also need to calculate effective Thevenin's resistance, which is where i found the problem.

Suppose we need to find the effective resistance between points 1 and 2 at the picture. First of all , what does "effective resistance between two points" even mean. Second, I would say "Rt = R2+R3+R4" and according to my workbook that is correct. But if we take a look at this example (at 3:50 for example), we will see that the "hanging" edge is also taken into account. Why ?

## Homework Equations

Thevenin's theorem

## The Attempt at a Solution

Like i mentioned, I simply used "Rt = R2+R3+R4" which turns out to be correct. Why does the guy in the video take that other edge into account??[/B]

The effective resistance between two points means, if you were to put an Ohmmeter across those points, that's the resistance that it would measure.

I didn't watch the video, but it would appear from the still shot that the "hanging edge" you refer to is in the path of the imaginary Ohmmeter that you would use to measure the effective resistance you're looking for.

Oh. well thanks, I feel like an idiot now :D

irrationally said:
Oh. well thanks, I feel like an idiot now :D
:) Don't. Better to ask and banish all doubt than to leave it to muddy your thought processes forever!

## 1. What is Thevenin's theorem and how does it relate to effective resistance?

Thevenin's theorem states that any linear circuit can be simplified to an equivalent circuit with a single voltage source and a single effective resistance. The effective resistance is the resistance that would be seen by a load connected to the circuit, and it is the same as the Thevenin resistance.

## 2. How is the effective resistance calculated for Thevenin's theorem?

The effective resistance, or Thevenin resistance, is calculated by removing all voltage sources from the circuit and finding the total resistance seen between the load terminals. This can be done using standard methods such as series and parallel resistors, or using other techniques such as the delta-wye transformation.

## 3. Can Thevenin's theorem be used for nonlinear circuits?

No, Thevenin's theorem only applies to linear circuits. Nonlinear circuits cannot be simplified to a single voltage source and effective resistance.

## 4. How does Thevenin's theorem help in circuit analysis?

Thevenin's theorem simplifies complex circuits into simpler equivalent circuits, making circuit analysis easier and more efficient. It also allows for the calculation of voltage and current at any point in the circuit, even if the load is not directly connected.

## 5. What are the limitations of Thevenin's theorem?

Thevenin's theorem only applies to circuits with linear components and cannot be used for circuits with active elements such as transistors. It also assumes that the circuit is in steady state and does not account for transient effects. Additionally, the theorem is only applicable for DC circuits and may not accurately represent the behavior of AC circuits.