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 Resonance

  1. Aug 23, 2012 #1
    Having carried outan AC Resonance experiment recently, I find that I have missed a simple step in the procedure- or left it out of my lab book - grrr!

    For a parallel RLC circuit I was asked to observe voltage across the inductor (coil) at a constant current setting.
    I'm assuming the trace to be a peak at resonant frequency. Could someone confirm this & elaborate if possible, please.

    I didn't record this & although just a small part of the report I should include it.
    Last edited: Aug 23, 2012
  2. jcsd
  3. Aug 23, 2012 #2


    User Avatar

    Staff: Mentor

    The term "constant current" implies a DC condition, not an AC resonant condition. Could you please clarify?
  4. Aug 23, 2012 #3
    I think I know that the poster means that the AC current does not change. Constant current does not have to mean it is DC.
    They have said that there is a peak at the resonant frequency this sounds like a 100% AC question.
  5. Aug 23, 2012 #4
    Constant current setting probably refers to the combination of the position of the output dial on the power supply and the operating mode of the power supply.

    I expect the circuit consists of a load that is a parallel RLC circuit driven by a current source of constant amplitude and variable frequency. The voltage across the load will thus be a maximum when the impedance of the load is a xxxxxx . This xxxxxx occurs when .....................
  6. Aug 24, 2012 #5
    Yes, the current is A.C & is set to an output which does not change & the frequency is swept over a range.

    RLC circuit.jpeg
  7. Aug 24, 2012 #6
    We have done more or less the same thing but for a series circuit. In that case the voltage was kept constant (it was shown on a multimeter) and we observed the AC voltage across the series resistor using an oscilloscope. Resonance could be obtained quite easil by changing the frequency.
  8. Aug 24, 2012 #7
    Roodles, do you have some data from your experiment? Do you have values for the components and settings on the signal generator?

    [ a scan of your lab-book would work too ]
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook