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: KVL application

  1. Apr 15, 2015 #1

    what is the process to apply KVL exactly?

    we know nothing in a loop, apart from that it consists of 2 batteries with known polarity and 2 resistors.

    what do we do?

    we assign arbitrarily the currents to each of the branches that compose the loop? and then we assign polarities to the resistors?

    or we assign arbitrarily polarities to the resistors in the loop and apply kvl based on that and if we find negative values, we just invert the polarity?

    I am a bit confused

    To give you an example:

    1) according to the first method (we take resistor polarities based on the arbitrarily taken currents)
    in left loop, we have V1-Vr3-Vr1=0
    in right loop, we have V2-Vr2+Vr3=0
    2) according to the second method (we assign polarities of resistors arbitrarily)
    in left loop, we have V1-Vr3-Vr1=0
    in right loop, we have V2-Vr2+Vr3=0

    which are the same, but the website of this example gives:


    Last edited: Apr 15, 2015
  2. jcsd
  3. Apr 15, 2015 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Which website?
  4. Apr 15, 2015 #3
  5. Apr 15, 2015 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    I think it's just a typo.

    He later writes:


    which implies using opposite signs for VR3 .
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted