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: AC Voltage output across Resistor

  1. Jun 10, 2010 #1
    1. The problem statement, all variables and given/known data
    For the circuit below (attached) plot the amplitude of AC voltage across resistor as a function of the angular frequency of the ac source.

    2. Relevant equations
    ZR = R

    3. The attempt at a solution
    I'm not really sure about any of this. Across the resistor, the complex impredence is just R and so has no dependence on the angular frequency, but just plotting a stright line with amplitude IR can't be worth 5 marks (which is the marks for this question). Can someone explain this to me?

    Attached Files:

  2. jcsd
  3. Jun 10, 2010 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    The current I varies with frequency.
  4. Jun 11, 2010 #3
    the L & C impedances vary with frequency.
    So, the voltage across the resistor should also vary as it is in series with the L-C combination.

    Find out the total impedance of the parallel combination of L & C (which is a function of w).
    Now R is in series with this combo-impedance.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook