Transient response of LCR circuits

Objective

Explore the oscillatory nature of L and C in series. Resonant frequency of series LC circuit is given by f_0 = 1/(2\pi\sqrt{LC}). The damping factor is R/(2\sqrt{LC}), and it is equal to 1 for critical damping (http://en.wikiversity.org/wiki/RLC_circuit). Depending upon the value of C/L and R, the response could be under-damped, critically-damped or over-damped.

_images/RLCtransient.svg _images/RLC-curves.png

Procedure

  • Start with the coil and 0,1~\mu F capacitor
  • Click on 5->0V STEP. Adjust x-axis and repeat if required.
  • FIT the graph to find the resonant frequency & Damping.
  • Repeat with a resistor between OD1 and the inductor.
  • Repeat the experiment with different values of L, C and R

Discussion

We have used the 3000 turn coil and a 0,1~\mu F capacitor. The voltage across the capacitor after a 5 to 0V step is shown in figure. The measured resonant frequency tallies with f = 1/(2\pi\sqrt{LC}), within the component tolerance values.