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Homework Help: Reisitor Problem

  1. Mar 1, 2005 #1
    You are given a number of 10 ohm resistors, each capable of dissopating only 1 w without being destroyed. What is the minimum number of such resistors that you need to combine in series or parrallel to make a 10 ohm resistance that is capable of dissipating at least 5w? Hmm i know the answer is 3 series of 3 in parrallel but i dont know how to work to achieve this answer.

    Also when doing circuit problems do u find the current at each resistor? or each branch?
     
  2. jcsd
  3. Mar 1, 2005 #2

    dextercioby

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    Each branch from a circuit has a current (or intensity,the old name).So that should be very clear.As for your problem,it's not that simple.U must take into acount that
    [tex[ P=RI^{2} [/tex] and a bunch of inequalities forthe various powers dissipated in resistors.Plus u'll need to know the formulas giving the equivalent resistance for a seris arrangement & for a parallel one,respectively.U should (hopefully) be able to write down a system of inequalities which MUST BE SOLVED INTO [tex] \mathbb{N} [/tex].

    Good luck!

    Daniel.
     
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