• Support PF! Buy your school textbooks, materials and every day products Here!

Find equivalent resistance in this circuit

  • Thread starter Hyperfluxe
  • Start date
  • #1
35
0

Homework Statement


http://session.masteringengineering.com/problemAsset/1515645/4/Steif.ch02.p28.jpg
Find the equivalent resistance between node A and B, knowing that Rab = Vab/Iab

Homework Equations


KCL and KVL, I know.


The Attempt at a Solution


There is nothing in series or parallel here, so what I did is set up KCL equations and KVL loop equations (top and bottom loops), so 6 equations with 6 unknowns and I can find Iab. I don't know how to find Vab though...
 

Answers and Replies

  • #2
gneill
Mentor
20,702
2,704
You don't find Vab, you stick a voltage source there (value of your choosing, or just leave it as a variable, "Vab"). The equivalent resistance Rab is given by the ratio Vab/Iab.

Presumably the Vab variable will cancel out in the workings leaving you with an expression for Rab in terms of R alone.
 
  • #3
35
0
I'm still confused though, is my method of finding Iab correct?
 
  • #4
gneill
Mentor
20,702
2,704
I'm still confused though, is my method of finding Iab correct?
Well, the approach of finding Iab given a source voltage Vab is correct. But you haven't shown the details of your work so it's not possible to say more.
 
  • #5
CWatters
Science Advisor
Homework Helper
Gold Member
10,528
2,294
I'm still confused though, is my method of finding Iab correct?
You don't need to solve the equations to find Iab or Vab their own.

Rab = Vab/Iab

so reaarange the equations until you get one for the ratio Vab/Iab in terms of the resistors only.
 

Related Threads for: Find equivalent resistance in this circuit

Replies
1
Views
9K
Replies
12
Views
3K
Replies
19
Views
785
Replies
3
Views
2K
Replies
2
Views
6K
Replies
5
Views
460
Replies
3
Views
13K
Replies
4
Views
3K
Top