AC Circuit


The first graph you see shows the voltage across each component as a function of time. The black curve is the voltage coming from the power supply (note that this does not change amplitude). The blue curve is the voltage across the resistor - it is directly proportional to the current, so it shows the phase relationship between the power supply voltage and the current.

The red and green curves show the voltage across the capacitor and the inductor, respectively. Note that the voltage across the inductor always leads the current in the circuit by 90 degrees, no matter what the frequency. Similarly, the voltage across the capacitor is always 90 degrees behind the current.

Modify the frequency, and note in particular what happens at the resonance frequency, when the black and blue curves are in phase.

You can view the other graph, showing the rms current in the circuit, by clicking on the box marked "Voltage". Again, note in particular what happens at the resonance frequency.

By placing the mouse over any component (the inductor, for instance) you can see its value, the voltage across it, and the phase angle of the voltage across it (relative to the voltage of the AC source).


This simulation is based on a physlet by Wolfgang Christian, part of the physlets page at Davidson College.