need help calculating current

Discussion in 'Homework Help' started by darkknight, Oct 7, 2009.

  1. darkknight

    Thread Starter Active Member

    Oct 7, 2009
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    I am starting to learn and i am having some problems with this exercise, i was wondering if someone could help me out the resistor of 4ohms is reall throwing me off

    by the current law i know the current leaving is the same entering It = I1+I2

    It=9A
    but at i1 i am getting 12a and i2 getting 6a


    please help
     
    Last edited: Oct 7, 2009
  2. crashcash

    New Member

    Oct 7, 2009
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    0
    let's recalculate the value of Rt. the two 3 ohm resistors at the far right are in series. they add to 6 ohms. that value is in parallel with the 3 ohm in the middle. calculating that will give you 2 ohms. that 2 ohm resistor is in series with the 4 ohm resistor and will give you an Rt of 6 ohms. therefore It is 6 amps. (ohm's law) next the 4 ohm resistor has that same 6 amps current flowing through it. therefore it's voltage must be 24 volts. the remaining 12 volts (36-24) is across the 3 ohm resistor in the middle. therefore it gets 4 amps. because i1 is 4 amps and itotal is 6 amps, the difference of those 2 currents is 2 amps. that flows through the two 3 ohm resistors in series.

    hope that helps

    crashcash

    PS it's always a good idea to label all the components in the circuit.
     
  3. darkknight

    Thread Starter Active Member

    Oct 7, 2009
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    but adding all the voltages doesnt that have to be equal to 0 by KVL?? tahnks for you response, sorry if the question is stupid i am just trying to learn
     
  4. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Last edited: Oct 7, 2009
  5. darkknight

    Thread Starter Active Member

    Oct 7, 2009
    41
    0
    thanks for your help, i understand it better now
     
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