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Homework Help: Yet another question on circuits!

  1. Nov 2, 2005 #1
    i've been given this circuit, i know the e.m.f. and internal resistance, it has 2 resistors connected in parallel so i can work out Rtotal, but i need to work out the current through one of the resistors. can anyone point me in the right direction?
    thanks :biggrin:
  2. jcsd
  3. Nov 2, 2005 #2


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    Homework Helper

    Well, once you know R you can calculate the total current. With the current, you can calculate the volt-drops certain resistances, etc. That's generally the approach to take.
  4. Nov 2, 2005 #3
    so do i take the e.m.f. as being the supply voltage in this case? cos i can't think of any other way to find it
  5. Nov 2, 2005 #4


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    Gold Member

    The internal resistance [of the battery] acts as if it were a resistor in series with the battery. You could find the ternimal voltage.
    [tex]V_{ab} = \varepsilon - Ir[/tex]

    [tex]\varepsilon[/tex] = Emf
    [tex]r[/tex] = internal resistance

    USing ohms law we get.
    [tex]IR = \varepsilon -Ir[/tex]

    Where [tex]R[/tex] is the 2 resistors in parallel.

    I'm sure you can take it from here.
    Last edited: Nov 2, 2005
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