How Do You Approach an Irregularly Shaped DC Circuit Problem?

In summary, the conversation is about a circuit problem involving a Y-delta transform. The individual resistances are given and the attempt at a solution involves using equations to solve for the total resistance. However, the mistake is pointed out that the resistors are taken in pairs, leading to different equations.
  • #1
Elbobo
145
0

Homework Statement


http://img144.imageshack.us/img144/9724/tricircuitxv4.jpg
http://g.imageshack.us/img144/tricircuitxv4.jpg/1/


Homework Equations



Re = R1 + R2 + R3

The Attempt at a Solution



I don't really understand this problem. I'm not sure how to approach it. I thought 5 = Rb + Rc, and I did that for all the rest of the resistors to solve the system but that was wrong.

Can someone just help me understand what the problem is asking and what it gives?
 
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  • #2
I would interpret it to mean that

Ra + Rb = 6

etc.

3 equations - 3 unknowns
 
  • #3
That's exactly what I did, and got a nice rational number - 3.5 (the answer is almost never rational). It's wrong.
 
  • #4
Elbobo said:
That's exactly what I did, and got a nice rational number - 3.5 (the answer is almost never rational). It's wrong.

I see what's wrong.

Ra + Rb = 6 || (5 + 6)

The equivalent resistance from one to the other includes the alternate series pair in parallel with the direct one.
 
  • #5
So you're saying Ra + Rb = (1/6 + 1/11)^-1?

Isn't that saying the total resistance of the first circuit equals only the sum of the resistances Ra and Rb?
 
  • #6
Elbobo said:
So you're saying Ra + Rb = (1/6 + 1/11)^-1?

Isn't that saying the total resistance of the first circuit equals only the sum of the resistances Ra and Rb?

Yes that's the calculation.

No, it's how the resistors are taken. Note the circuit is not symmetrical. You get pair-wise different equations.

There's 6 || 11 and 6 || 11 and 5 || 12
 
  • #7
Ah ok, thank you.
 
  • #8
Elbobo said:

Homework Statement


http://img144.imageshack.us/img144/9724/tricircuitxv4.jpg
http://g.imageshack.us/img144/tricircuitxv4.jpg/1/


Homework Equations



Re = R1 + R2 + R3

The Attempt at a Solution



I don't really understand this problem. I'm not sure how to approach it. I thought 5 = Rb + Rc, and I did that for all the rest of the resistors to solve the system but that was wrong.

Can someone just help me understand what the problem is asking and what it gives?

This is known as the Y-delta transform (though this question is probably to get you guys to derive the transformation to be covered in class!):
http://en.wikipedia.org/wiki/Y-Δ_transform
 
Last edited by a moderator:

Related to How Do You Approach an Irregularly Shaped DC Circuit Problem?

1. What is an irregularly shaped DC circuit?

An irregularly shaped DC circuit is a type of electrical circuit that does not have a uniform shape or structure. This means that the components and connections within the circuit may be arranged in a non-linear or asymmetrical way, making it more complex than a traditional, symmetrical circuit.

2. How does an irregularly shaped DC circuit differ from a regular DC circuit?

The main difference between an irregularly shaped DC circuit and a regular DC circuit is the arrangement of its components and connections. In a regular circuit, the components are arranged in a symmetrical and uniform manner, while an irregular circuit may have components arranged in a non-linear or asymmetrical way.

3. What are some applications of irregularly shaped DC circuits?

Irregularly shaped DC circuits are commonly used in electronic devices and systems that require complex and non-linear circuits. This includes advanced computer systems, electronic sensors, and communication devices.

4. How do you analyze an irregularly shaped DC circuit?

Analyzing an irregularly shaped DC circuit involves applying the principles of Kirchhoff's laws and Ohm's law to determine the voltage, current, and resistance at various points in the circuit. This can be done using circuit analysis techniques such as nodal analysis and mesh analysis.

5. How can you troubleshoot an irregularly shaped DC circuit?

Troubleshooting an irregularly shaped DC circuit involves identifying and isolating any faulty components or connections that may be causing issues. This can be done by using a multimeter to measure voltage and resistance at various points in the circuit, and visually inspecting the circuit for any visible damage or loose connections.

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