1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Circuit analysis problem

  1. Feb 6, 2016 #1
    1. The problem statement, all variables and given/known data
    upload_2016-2-7_0-19-43.png
    how did they get this ?? it is like a potential divider, can anyone explain...

    2. Relevant equations


    3. The attempt at a solution
    this is what i got

    upload_2016-2-7_0-23-1.png
     
  2. jcsd
  3. Feb 6, 2016 #2

    cnh1995

    User Avatar
    Homework Helper

    Are you familiar with node voltage method?
     
  4. Feb 6, 2016 #3
    yes i know about node voltage, i want the node at V_
     
  5. Feb 6, 2016 #4

    cnh1995

    User Avatar
    Homework Helper

    You can write the node voltage equations and rearrange them to get V_. There will be 3 principal nodes.Assume ground node at the bottom wire and proceed.
     
  6. Feb 6, 2016 #5
    upload_2016-2-7_1-34-9.png
    upload_2016-2-7_1-35-49.png
     
  7. Feb 6, 2016 #6

    NascentOxygen

    User Avatar

    Staff: Mentor

    View attachment 95408
    Your second term is correct involving V2, and if you had been consistent you'd have a corresponding correct expression involving V1. The method you are using for this is called Superposition.
     
  8. Feb 7, 2016 #7
    so this

    how can i rearrange this to equal this
    upload_2016-2-7_17-41-48.png
     

    Attached Files:

  9. Feb 7, 2016 #8

    cnh1995

    User Avatar
    Homework Helper

  10. Feb 7, 2016 #9
  11. Feb 7, 2016 #10

    cnh1995

    User Avatar
    Homework Helper

    Using cross multiplication, you will be able to cancel out Z2+Z3 in the denominator with that in the numerator. Then take Z3 common from the numerators and you are done.
     
  12. Feb 7, 2016 #11
    upload_2016-2-7_17-55-21.png
    i can do this ?
     
  13. Feb 7, 2016 #12
  14. Feb 7, 2016 #13
  15. Feb 7, 2016 #14
    when adding fractions why does the denominator for the Z1 Z2 become Z1*Z2 ?
     
  16. Feb 7, 2016 #15
    upload_2016-2-7_18-4-47.png
    i dont really understand the last step here
     
  17. Feb 7, 2016 #16

    cnh1995

    User Avatar
    Homework Helper

    How will you write this term in the denominator
    Z1+Z2Z3/(Z2+Z3) using cross multiplication? It is used to make the denominators same. It is basic algebra.
    e.g 3/4+2/3=[( 3×3)+(4×2)]/(3×4)=17/12.
    You can not directly cancel the terms like you did there.
     
  18. Feb 7, 2016 #17
  19. Feb 7, 2016 #18

    cnh1995

    User Avatar
    Homework Helper

    upload_2016-2-7_17-47-24-png.95451.png
    Consider only the first term i.e. the term before + sign. Apply the cross product rule in its denominator. What will you get?
    Similarly proceed for the next term. It is a matter of only one step.
     
  20. Feb 7, 2016 #19
  21. Feb 7, 2016 #20
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Circuit analysis problem
  1. Thevenins problem (Replies: 3)

Loading...