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: Finding the values of resistors

  1. Sep 28, 2013 #1
    1. The problem statement, all variables and given/known data
    In the problem i have to find the values of resistors using voltage divider, and use KVL to determine the currents.

    2. Relevant equations

    Vi= [Ri / (R1+R2+...+Rn)] * Vs

    1/Rtotal = 1/R1 + 1/R2 + ... + 1/Rn

    Ʃrise + Ʃdrop = 0

    3. The attempt at a solution

    In order for us to use voltage divider the resistors must be in series.

    Req = (40*R2)/(40+R2), but we still don't know the resistance of R2.

    However, later I tried to use the KVL equation to find the voltage for Req.

    -24+8+Veq = 0 → Veq = 16 V

    Then I used the voltage divider equation:

    Veq = [Req / (R1 + Req) ]* Vs // but again we have two unknowns here again

    And that's the point where I stuck, I know this problem is trivial but my brain cannot come up with anything else to solve this.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Sep 29, 2013 #2
    Using KVL, we know that Veq=24V-8V=16V. Using Ohm's Law, we can easily get R2=16V/1.6A=10 Ohms. The rest is obvious! :)
  4. Sep 29, 2013 #3
    Thank you very much :D
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted