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: Nodal analysis question

  1. Feb 6, 2014 #1

    I understand their method. However, if you use the node to the left of the 2 ohm resistor (the node where the voltage = 75 V) then you get:

    (75-Vx)/2 -10 = 0

    so 75-Vx = 20
    so Vx - 75 = -20
    Vx = 55 V

    But this is not 25 V as it should be?

    When doing nodal analysis, do you have to consider each node?
  2. jcsd
  3. Feb 6, 2014 #2


    User Avatar
    Gold Member

    You did not include the current through the 75 v voltage source. your first equation should have been
    (75-Vx)/2 -10 -(i3+0.4*Vx)= 0

    that being said when you do nodal analysis you should only do kcl's at nodes with unknown voltages. you know that the 75v node is 75 v above ground. So try a KCL at nodes Vx and V1

    does that make sense?
  4. Feb 8, 2014 #3
    Ah yes! Thanks a lot mate.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted