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Homework Help: Currents in three branches

  1. Feb 7, 2010 #1
    I am doing some work with electric circuits and just have a general question. With the concern of a given current in three branches of a circuit, is the total current the sum of the current through the resistors? Are they all equal, or does half of the current flow through each resistor? I think that they are all equal, but my partner in crime thinks that all of the total current flows through the smallest resistor. Which I highly doubt.

    I guess what I am asking is:

    concerning the currents in the three branches of the circuit: are they all equal, does half of the current flow through each resisotr, or does the total current flow through the smallest resistor; like my friend is suggesting.

    I would appreciate some feedback today if possible. Thanks!
  2. jcsd
  3. Feb 7, 2010 #2
    Without a diagram of your circuit I'll have to guess.
    Generally yes, the total current is the sum of the current through the resistors. This assumes you have two resistors in parallel.
    The current will be equal in two parallel resistors only if they are of equal resistance.
    If one is bigger than the other, the current in each will be different and in inverse proportion to the values. For example, if A is twice the resistance of B, the current in B will be twice that in A.
  4. Feb 7, 2010 #3
    Resistors in parallel each have the same voltage drop and resistors in series each have the same current. With this you can answer your question, kind of. Also with this information and Ohm's law you can derive both formulas for parallel and series resistance, see any physics book, or see:

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