Ohms Law Clarification Please

Discussion in 'Homework Help' started by stinky111, Apr 30, 2011.

  1. stinky111

    Thread Starter Member

    Apr 7, 2011
    39
    1
    Hi all,

    IF R1=13Ω, R2=42Ω R3=???Ω.


    V=230Volts & I=53amps.


    Calculate R3


    Im familiar with using Volts & Amps to get Resistance Total, but not sure with above when given 2 of the 3 resistance values.


    Using V & I to calculate I get:


    Rt = 4.339622Ω


    I thought it would make sense(in my head to) then -R1 & R2 values from Rt to give R3??
    Is this correct?? Thx
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    You can take an other approach to the problem.
    You know the total current.
    You know two resistor values.
    With the given voltage and the two given resistors,
    you can calculate the currents through these resistors.
    You can subtract the calculated currents from the total current.
    With this resulting current and the given voltage,
    you can calculate the missing resistor value.

    Succes,
    Bertus
     
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  3. dcarson7

    New Member

    Apr 28, 2011
    7
    1
    [​IMG]
     
    stinky111 likes this.
  4. stinky111

    Thread Starter Member

    Apr 7, 2011
    39
    1
    Thx for replies..
    The circuit is identical to the one you provided,
    Just to clarify I will not be building this circuit, it was a question from a past exam that I have been studying & trying to familiar myself with,
    thanks for your time guys..
     
    dcarson7 likes this.
  5. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    @dcarson7:
    The homework help forum is to get help.
    Please do NOT give complete answers anymore.
    Only hints and suggestions to solve the problem are welcome.

    @stinky111
    You can take a look at this page of the eBook:
    Simple parallel circuits

    Bertus
     
    Last edited: Apr 30, 2011
  6. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
  7. dcarson7

    New Member

    Apr 28, 2011
    7
    1
    @bertus - Advice noted. , when I said check RT with R3 value, I was hinting for the OP to make some effort there.
    There was nothing asked regarding power but I felt it'd be wise to inform someone new that considerations needed to be made.

    @Adjuster - solid point, anything high power I tend to run away from :)
     
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