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Help! Superposition, Nortons, Thevenins

  1. Jan 16, 2007 #1
    Hi, having major problems with this set homework. The task is to find the current through the 5ohm resistor by means of:

    • Super Position Theorem
    • Nortons Theorem
    • Thevenins Theorem

    [​IMG]

    ANY help will be greatly appreciated. Thanks.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jan 16, 2007 #2

    cristo

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    Welcome to PF MrTap. Please note that we cannot help with homework questions, unless you first post your attempts at the problem.
     
  4. Jan 16, 2007 #3

    ranger

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    Gold Member

    MrTAP, you will not receive any help if you do not show your attempt. Since this is such an elementary circuit where these theorems can be easily applied. I suspect that you do not have a proper understanding of these theorems.
     
  5. Jan 17, 2007 #4

    lax

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    Hi,

    I am attaching a Document here, which will help you understanding the three network theorems with illustration as well.

    I am just giving you an analogy between your problem and the Illustration shown in the Document so that it will be easy for you to solve your problem.

    In Illustration:
    R1 = 4 ohm, R2 = 2 ohm, R3 = 1 ohm, B1 = 28 V, B2 = 7 V

    In your Problem:
    << Explicit solution removed by berkeman >>

    Regards,
    Lax.
     

    Attached Files:

    Last edited by a moderator: Jan 17, 2007
  6. Jan 17, 2007 #5

    berkeman

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    Lax, do not post complete solutions to homework problems -- that is against the PF rules. I approved your attachment because it is general in nature, and may help the original poster (OP) figure out the problem.
     
  7. Jan 17, 2007 #6
    K sorry :smile: Didn't read forum rules on this. Well it's a new course, very basic electrical theory so I needed this a like a 'guideline' to doing it....I'll have an attempt to tommorow and post. Thanks for Reading.
     
  8. Jan 23, 2007 #7
    Super Position Attempt

    OK. I made an attempt, please can you take a look at the attached word document I made. I still think the answer is wrong though.

    Super Position only at the moment.

    EDIT: BTW on the first pciture I posted, the 3V Battery symbol should be the other way around. (Like in my word document)
     

    Attached Files:

  9. Jan 23, 2007 #8
    Yup, that's what I got too. If there was a reference arrow drawn already to show the direction, you'd have to make sure your answer was flowing in the same direction, and if your answer was flowing opposite of this direction then change your answer to negative

    But if there's not one, I'd draw it on there once I knew the direction just incase I needed to know later
     
    Last edited: Jan 23, 2007
  10. Jan 24, 2007 #9

    lax

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    MrTap,
    Did u go through the document which I attached in my last mail.
    If you go through it, you can understand all theorems.
    Anyway I worked out your problem.
    Answer : << final answer deleted by berkeman >>
     
    Last edited by a moderator: Jan 24, 2007
  11. Jan 24, 2007 #10

    berkeman

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    Darn it lax, STOP doing that. I told you before that we do not post solutions here in the homework forums. Do NOT do it again. Warning points issued.
     
  12. Jan 24, 2007 #11

    lax

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    ok sorry 4 that.
    But I think he has attempted the Question that's why I tried to give the solution
     
  13. Jan 25, 2007 #12

    berkeman

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    That's BS. You've been warned multiple times. It happens one more time, and you're banned from the PF. You could have a great future here, lax. Believe me, we appreciate help in the homework forums. We provide a lot of value here. One more time, and poof....
     
  14. Jan 25, 2007 #13
    I'm failing to see the point of this forum. :frown:

    You cant say what forumlae to use, cant say which method to use, cant say the answer....wow. Just.

    The best way of learning is to see the answer and work upto it. bb I guess PF.

    <Intentional misquote removed by moderator.>
     
    Last edited by a moderator: Jan 25, 2007
  15. Jan 25, 2007 #14

    Moonbear

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    The best way of learning is to put the effort into working on the problem yourself. We can help you when you get stuck, or ask questions to lead you toward finding the right way to work out the problem, or point you toward the correct formulae, or show you where you have used one incorrectly, or clarify areas where you are misunderstanding a concept, but it's still your homework, not ours; the homework helpers have already passed the subjects they are helping with. Many of us are educators as well, either at high schools or universities.

    From experience, I can tell you that the best way to solve a problem is NOT to be handed the answer and then find a way to get to that answer. It is also not being handed a complete solution and just memorizing the steps in that solution. In the real world, nobody hands you the answer and tells you to solve toward it, and that won't happen on an exam either. You need to learn to start with the problem to find your own solution, and understand the concepts well enough that you can figure out what to do next on your own. That is what we help with.

    We want you to learn the subject well, not just find the fastest way to get through it. Our hope/expectation is that the students asking questions here today will be our scientific colleagues in the future, so we really want you to learn it the best possible way, not just the easiest. Give it a little time and as you start understanding the subject better, you'll see how much more enjoyable it is. :smile:
     
  16. Jan 25, 2007 #15
    I stand by my original statement. This forum does not help. Sorry for my difference in opinion, even though my opinion is fact. I regret registering in this forum. I wil not post again, sorry for wasting your time.

    I only thanks Lax for 'trying' to help
     
  17. Jan 25, 2007 #16

    ranger

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    What original statement? You also seem to have a narrow definition of "help". As stated in the guidelines, we will not do your homework for you. Homework helpers are here to provide hints so you can think about the problem in a different way. If you [and Lax ] think that the purpose of PF is to "hold hands", then you are seriously misunderstanding.

    Help doesnt necessarily come in the form of a forumla, methods, or direct answer...
     
  18. Jan 25, 2007 #17

    berkeman

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    If you do end up coming back, MrTAP, please check out the sticky thread called "Best Homework Posts" to see how this all works. It works pretty darned well most of the time.
     
  19. Jan 25, 2007 #18
    I hope you are not serious about this forum being no help. I've asked questions here for 4 years of undergraduate education. I've always received fantastic hints and help. You are in the wrong here and should show some respect.

    What you want is a straight up answer. Therefore, this specific forum is not for you and not posting again is probably the best solution.
     
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