RLC Circuits (AC)

Applet by Fu-Kwun Hwang

This is a RLC series circuit simulation (with AC Voltage source) java applet. This applet will show you the physics properties of an R-L-C circuit driven by a harmonic voltage source C

1. The peak value of AC source is fixed at 10.0 V and the resistor is 1.0 k.
2. Parameters you can change:

  1. The period of the AC source (enter into the text field). Its units can be G s , ms (10-3s), us(10-6s), ns(10-9s).
  2. You can change the inductance G: Click the mouse within the inductance region (blue coils). Click the left mouse button to decrease its value. Click the right mouse button to increase its value. The increase is determined by the delta* drop-down option.
  3. You can change the capacitance with the same method.
  4. Red Curve: V Yellow Curve: VR Blue curve: VL Green curve: VC
  5. The small white circle simulates the AC current; its velocity is proportional to the current I.
  6. If the mouse button is within the curve (time-voltage) region, the coordinate of the mouse will be translated and displayed. Click near (time, voltage)=(0.s, 10.0v) and drag the mouse up and down to change the y scaling factor.
  7. Press either mouse button to suspend the animation. If you click the left mouse button, the animation will resume after you release. If you click the right mouse button, the animation will resume after you re-click.
  8. Press Reset button to reset parameters.
  9. Press Quit or Close the window to Quit.


1. Phase between VC(Voltage of capacitor) and VL(Inductor)
2. Phase between VR(Resistor) and VL or VC.
3. Relation between VL and oscillator frequency f= 1/T(period). How can one increase VL?
4. Relation between VC and oscillator frequency. How can one increase VC?
5. VR is propotional to I (current). How can one increase the current? What is the relation between VL and VC when I is at its maximum?
6. V = VR + VL + VC
7. In the above picture, VL(blue) > V(red). Why?