1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Circuits-are my KVLs wrong?

  1. Feb 5, 2012 #1
    I attached the problem. I'm writing the KVL for each separate loop. For my purposes, I will only write the first two.

    i1=1st loop (one on the left) current
    i2=2nd loop current (loop in the middle)

    Loop 1: 12-12*i1-10(i1-i2)-6*i1=0
    Loop 2: -30(i2-i1)+10(i2-i1)=0

    The solutions differ with mine however that for loop 2 they have -30(i2-i1)-10(i2-i1)=0

    Am I wrong?
     

    Attached Files:

  2. jcsd
  3. Feb 5, 2012 #2

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    I agree more with the solution version -- apart from the fact that it's (i2-i3) that goes with the 30 ohm resistor.

    The way I remember it is: when traversing around the loop, when going in the same direction as the current then it's a voltage drop, therefore you get a "-" sign. When going against the current direction it's a voltage rise, and therefore you get a "+" sign.

    So, if we agree that we traverse the middle loop clockwise, and the currents are all defined as clockwise as well, then it should be "-" for all the i2 terms and "+" for i1 and i3 in the middle-loop equation.

    Hope that helps.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Circuits-are my KVLs wrong?
Loading...