5L20.18 Driven RLC Circuit


RLC circuits, resonance, phase shift, phasors


A function generator drives a series RLC circuit. The frequency response can be seen in an oscilloscope.



  • [1] Resistance box
  • [1] Inductor
  • [1] Capacitor
  • [1] Oscilloscope
  • [1] Function generator
  • [3] BNC plug to banana jack adapter
  • [8] Banana cable
  • Power bar (if necessary)
  • Extension cord (if necessary)

Classroom Assembly

  1. Connect the RLC circuit to the function generator using an adapter and banana cables.
  2. Connect the oscilloscope to two elements in the circuit. Be careful to ground the measurements at the same point.


You can obtain a graph showing the frequency response of the circuit by sweeping the frequency on the function generator and showing the voltage across the resistor.
  1. Check that an oscilloscope channel is measuring the voltage across the resistor.
  2. Set the function generator to continuously sweep through the resonance.

A common measurement is to compare the phases of the inductor and the resistor voltages.

  1. Check that the oscilloscope channels are connected to do measurements across the right components.
  2. Invert the signal on the channel that has a reversed connection.
  3. Change the frequency to see the phase shift across different regimes.


Additional Resources


  • PIRA 5L20.18


  • Don't attempt this at home!

Last revised

  • 2020


  • The function generator is a floating source, so the oscilloscope can do two measurements as long as both are grounded in the same place.
  • Using presets on the function generator will make the demo go faster.

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If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.