series parallel circuit

Discussion in 'Homework Help' started by locke3, Jun 3, 2012.

  1. locke3

    Thread Starter New Member

    Jun 3, 2012
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    Hey guys, new to the forum. I have what I think will be an easy question for someone. see attached picture.

    The question is....how do you calculate the voltage drop at R2 and the current though R3? I believe the total current to be .396 A and the total resistance to be 30 ohms. I know the answer for R2 is 3V but when I calculate it I get 6V. Any help would be great!
    Thanks again
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Show as your solution first.
     
  3. locke3

    Thread Starter New Member

    Jun 3, 2012
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    For the voltage drop at R2
    I took the current through the circuit .4 and multiplied it by the resistance in R2 and R3 which was 15Ω. My calculated voltage drop was 6.
     
  4. Jony130

    AAC Fanatic!

    Feb 17, 2009
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  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Half the current flows through R1.
     
  6. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    HINT: erase R1, it's irrelevant to the voltage forced across the right branch.

    Combine the two lower parallel resistors (R2 and R3) into one equivalent. Use that value to set up a voltage divider in the right circuit branch. The voltage across the lower equivalent resistor appears across EACH of the two resistors combined (R2 and R3).... so you can use that voltage to directly calculate the current through each one.
     
  7. locke3

    Thread Starter New Member

    Jun 3, 2012
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    Thank you guys.....I understand now!!!
     
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