 
Caltech LRC Laboratory
This Java applet is intended to show you how a system of a
resistor, a capacitor and an inductor react with one another in a system.
There are a couple of important limitations of this system

You can't reorganise the components, or apply the input at
different places

You can't observe voltages other than those coded in the
demo

Components set to zero are still shown
Notes
 Blue is used for voltage
 Red is used for current
 Stop  shows amplitude and phase
 Run  shows rotating phasors illustrating the exp(jwt)
dependence
 Step  increments the time by a small step
Outline instructions to illustrate key ideas
 Set L to 0 (to exclude the inductor)
 Set C to 0 (to exclude the capacitor)
 Set R to 5 ohms
Note: the graphic display still shows the L and C despite the fact that both
have been 'excluded'. You need to think of them as shortcircuits in this
illustration
 Vary the voltage using the slider
 Press Start  NB anticlockwise rotating phasor sketches out a sinusoidal
waveform
Note that the time axis is not 'real' time  it is 100 times slower.
Inductive reactance
 Vary the frequency and voltage using the sliders and observe the effect:
also, note that current and generator voltage are in phase.
Vary the resistance and note that while the current varies, the phase does
not change
 Press Stop, then Step, repeatedly, until the Blue & Red arrows lie at
0 (horizontal, pointing to R)
 Set the frequency to 50 rad/s (about 8 Hz); set voltage to 25 rms; set R
to 5 ohms
 Add some inductance, gradually, up to about 60 mH.
Note how the red current phasor begins to lag behind the a/c/wrotating
voltage phasor. Observe that the CIVIL mnemonic correctly predicts this.
 Vary L  a higher value increases the phase lag
 Vary f to show how the phase and amplitude of the current are affected
Capacitive reactance
 Reduce L to 0 (NB the blue/red phasors now coincide)
 Set f to 100 rad/s
 Set C to 5 mF
Note that the red phasor now leads the blue voltage phasor
 Change C and note that an increase reduces the phase lead
 Change f and note that increasing it reduces the phase lead
Resonance
 Set the capacitance to 8 mF, f to 50 rad/s  I
will lead V by about 30 deg.
 Now set R to 2, V to 14 rms
 Slide the L slider down and note how increasing L reduces the phase lead
seen.
At a certain value of L, the current neither leads nor lags. The
inductive and capacitive reactance have cancelled. This happens at one
characteristic frequency: the resonant frequency.
