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!

Homework Help: Using Kirchoff's Rules

  1. Nov 15, 2012 #1
    My loop 1 equation is I1R1 + I2R2 + E1 = 0
    simplified to: 4I1 + 2I2 + 28 = 0
    Loop 2: I3R3 - E2 - I2R2 = 0
    simplified to: 1I3 - 7V - 2I2 = 0

    And my node 1 equation is: 0 = I1 + I2 + I3

    So doing algebra.. I get my I1 to equal 7.. which doesn't match with the -5A for I1 as given in the problem.

    Are my equations wrong? Or is my algebra wrong?

    Attached Files:

  2. jcsd
  3. Nov 15, 2012 #2


    User Avatar
    Homework Helper
    Gold Member

    Loop 1 equation is wrong. No need to go further till that's fixed. I think you are trying to use the I references from the problem. Don't. Use only Iloop1 and Iloop2.
  4. Nov 15, 2012 #3
    Okay well I changed my node equation to I1 = I2 + I3 and got the right answer in the end.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook