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: A Question about Kirchoff's Voltage Law

  1. Oct 13, 2013 #1
    Hello Guys

    My Question about Kirchoff's Law is : why in this Example
    we considered that E2 is a Voltage Drop not a Voltage Rise ??

    i mean why we didn't say that : +E2-V1-V2+E2=0 ???


    and Thanks Guys :)) !!
  2. jcsd
  3. Oct 13, 2013 #2

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    It's because the loop has a direction. In this case, the loop is clockwise, making E1 positive but E2 negative.
  4. Oct 14, 2013 #3
    Pick a direction for your analysis. Assign a sign to all the voltage rises, and the opposite sign to the voltage drops. The sum of all the voltage rises =the sum of all the voltage drops around the circuit.

    In your example, the current loop is clock wise, so the current flows into the negative side of E1 (voltage rise), and into the positive side of E2 (voltage drop).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted