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: Maximizing voltage across a load resistor?

  1. Feb 22, 2010 #1
    Hey, so I have this loop circuit that has some input voltage V in series with a resistor with a resistance of R and another in series resistor that is my load resistance, lets call it G. V and R are not variables, only G is.

    I know that because of Jacobi's law, to maximize the power dissipated by the load resistance, you have to have G = R.

    But I'm wondering how i should maximize the voltage drop across the load resistor? I just can't figure out how to write an equation and go from there.

    Also, how can i maximize the current going into the load resistor?

    Please help,
    Thanks
     
  2. jcsd
  3. Feb 22, 2010 #2

    berkeman

    User Avatar

    Staff: Mentor

    What is the voltage divider equation? That is what you use to do what you are asking about.

    Assuming that V and Rs are fixed, you maximize the output voltage with an ______ circuit, and maximize the output current (a different situation) with a _______ circuit.
     
  4. Feb 23, 2010 #3
    You mean kirchoffs voltage eqn?

    Its V - IR - IG = 0

    im starting to think that i can maximize the voltage drop on the load resistor G by maximizing the resistance of G though...still don't know if thats right.
     
  5. Feb 23, 2010 #4
    The voltage drop across the load resistor is given by VG=VG/(R+G), to find the maximum value of this function find when the derivative equals zero, so when R/(R+G)2= 0, which is when G equals infinity...basically the bigger the resistance the bigger the voltage drop across it.. if I am understanding your question..now to maximize the current going into the load resistor, well I=V/(R+G)...what would give a maximum value for I if G is the only variable?
     
  6. Feb 23, 2010 #5
    OH! so minimizing R+G for current..i see.

    Thanks a lot guys.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook