RC circuit black box circuit modeling

In summary, the red mystery box contains a 20, 50, 100, and 200,000 ohm resistor. Testing A-B showed 60k, testing A-C showed 140k, and testing B-C showed 120k ohms. The Attempt at a Solution is to try to find the right values for 60k, 140k, and 120k ohms by measuring after the 20 and 50 ohm resistors, and before the 200,000 ohm resistor returns to its original value. This may just be a TA's lazy work, as the diagrams show no progress after an hour of trying.
  • #1
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Homework Statement


I have a red mystery box which contains a 20, 50, 100, and 200,000 ohm resistor (one of each and ONLY one.)

There are three terminals on the box you can plug a voltmeter into... testing A-B I got 60k, testing A-C I got 140k, and testing B-C I get 120k ohms. So this is a bit of a puzzle.

I'm aware of general and relevant equations.

The Attempt at a Solution


I really struggle with this for some reason. It's been a while with RC circuits.

These are pretty large values and it means that no matter what two places you pick, at least some of the current must flow through the 200K ohm resistor I think. Ok I think I can do this... it seems I need to somehow reduce the resistance of the 200,000 ohm resistor by some percentage. But I DO NOT know how to do this without either making the resistance JUST a flat 60 ohms for instance, or I either just make a map so that I get 200,050 ohms...

I tried thinking of something like... starting with the 200K resistor, then as you move along the circuit splits to a parallel junction with 20 and 50. The junction does not connect back to one line. One end leads off from the 20, and another end leaves from the 50 ohm resistor for instance. This sort of arrangement looked good for a moment but the thing is I think that "current" or whatever is measured won't pass through the other resistor at the parallel junction, right!?? So that just becomes 200,020 or 200,050 ohms and it just adds...
I was hoping that for instance if the 20-50 junction came back together, I think I could feasibly squeeze out the right values 60k 140k and 120k if you measured immediately after the 20 or 50 ohm resistor, and before it came back together.
 
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  • #2
How is this an RC circuit? It contains resistors only, no capacitors.

Are you sure that the 20, 50, and 100 values are Ohms and not k Ohms? I don't see how it would be possible to have all measured results above 170 Ω, let alone in the kΩ range otherwise. Unless it's your measurements that are not correctly scaled?

Rather than describing circuits in text form it would be much better to post sketches of your ideas. A circuit diagram conveys information more efficiently without the possibility of misinterpretation.
 
  • #3
I see what you mean. Maybe the resitances are 20kohm 50kohm and so. Anyway I would try first to work with a t or delta model to see which values of recistance I get. Still I think there is something missing in the problem statement.
 
  • #4
Ohhhhhhhhhhhh you might be right there...

This may just be stupidly lazy TA's at work... I spent an hour trying these diagrams.

Thanks both.
 

FAQ: RC circuit black box circuit modeling

1. What is an RC circuit black box circuit model?

An RC circuit black box circuit model is a simplified representation of an RC circuit that is used to analyze the behavior and characteristics of the circuit. It is a commonly used tool in circuit analysis and is helpful in understanding the response of the circuit to different inputs.

2. How does an RC circuit black box circuit model work?

The RC circuit black box circuit model uses a combination of resistors and capacitors to represent the behavior of an RC circuit. The resistors represent the resistance in the circuit, while the capacitors represent the capacitance. By using these components, the model is able to simulate the charging and discharging of the capacitor and the flow of current through the circuit.

3. What are the key components of an RC circuit black box circuit model?

The key components of an RC circuit black box circuit model are resistors, capacitors, and a voltage source. The resistors and capacitors are used to represent the behavior of the circuit, while the voltage source is used to provide a constant input voltage to the circuit. Other components, such as switches and diodes, may also be included depending on the complexity of the circuit.

4. What are the advantages of using an RC circuit black box circuit model?

One of the main advantages of using an RC circuit black box circuit model is its simplicity. It provides a simplified representation of the circuit, making it easier to analyze and understand its behavior. It also allows for quick and easy calculations of key parameters, such as time constants and voltage levels, which can be useful in designing and troubleshooting circuits.

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