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!

Resistor network question Cant get it

  1. Feb 12, 2012 #1
    1. The problem statement, all variables and given/known data
    A network of 5 resistors is constructed to a 12.0V emf. the total current in the circuit is 12.0A. determine, draw and label the configuration for the network of resistors
    R1=1ohm, R2=1ohm, R3=1ohm, R4=1ohm, R5=4ohm


    2. Relevant equations



    3. The attempt at a solution
    i figured that the overall resistance must be 1Ohm using Ohm's Law but I've filled up like 2 pages with stuff that doesn't add up. any one have any suggestions or maybe an easier way to approach the problem.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Feb 12, 2012 #2

    gneill

    User Avatar

    Staff: Mentor

    Hi biochemguy, Welcome to Physics Forums.

    Could you solve the problem if there were only 4 resistors?
     
  4. Feb 12, 2012 #3
    we have to use all 5. it would be way easier if i didn't have the 4-ohm resistor. that's the one that is throwing a monkey wrench in my attempts. if i had 2 pairs of the 1 ohm resistors in parallel that would give me the 1-ohm right? (1/2+1/2)?
     
  5. Feb 12, 2012 #4

    gneill

    User Avatar

    Staff: Mentor

    Right. So the question is, is there a configuration of the four 1 Ω resistors that gives you the required 1 Ω total, but which provides a couple of nodes where you could attach the 4 Ω resistor where it would not make any difference (it would not conduct any current)?
     
  6. Feb 12, 2012 #5
    not quite sure what you mean. how could you make it not conduct any current?
     
  7. Feb 12, 2012 #6

    gneill

    User Avatar

    Staff: Mentor

    What is required for current to flow through a resistor?
     
  8. Feb 12, 2012 #7
    Voltage? sorry if i'm not up to speed, its just physics is definitely not my forte.
     
  9. Feb 12, 2012 #8

    gneill

    User Avatar

    Staff: Mentor

    Yes, a potential difference across the resistor is required. So if you can lay out the other four resistors in such a way that two nodes happen to have the same potential, anything connected across those two nodes will have the same potential -- so no potential difference.
     
  10. Feb 13, 2012 #9
    thanks gneill. i ended up figuring it out in the library this morning. I think he just wanted it in a single loop, but you seem to know way more than me so hopefully you can help when i have more question.
    thanks again though
     
  11. Feb 16, 2012 #10
    put 3 1 ohm resistors in parallel to each other then connect a single 1 ohm resistor in series with the previous combination. Then connect the last 4 ohm resistor in parallel to the whole combination, the resulting circuit will give you resistance equivalent to 1 ohm.

    Thus the circuit applied to 12 volt source will give 12 ampere current through circuit.
     
  12. Feb 16, 2012 #11

    Its a very good approach that you have posted over here, it would be of help to me if you can post a method or a diagram that how would you arrange these nodes and resistance in such order.
     
  13. Feb 16, 2012 #12

    gneill

    User Avatar

    Staff: Mentor

    Think of a balanced bridge circuit. No current flows through the bridge.

    attachment.php?attachmentid=43997&stc=1&d=1329403977.gif
     

    Attached Files:

  14. Feb 16, 2012 #13

    Thanx !
     
  15. Feb 16, 2012 #14
    Can you solve this problem plzz ! I am getting answer -5 volts !
     

    Attached Files:

  16. Feb 16, 2012 #15

    gneill

    User Avatar

    Staff: Mentor

    New problems should be posted in their own, new threads. Also, you must show your own work/reasoning before we can know how to help you.
     
  17. Feb 16, 2012 #16
    ok. Didn't knew that !
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Resistor network question Cant get it
  1. Resistor Network (Replies: 2)

  2. Resistor network (Replies: 4)

  3. Network of resistors (Replies: 3)

Loading...