Part III – Resonance

An LC circuit initially charged will oscillate with energy flowing back and forth between the inductor and the capacitor. A circuit like this loses very little energy because neither inductors nor capacitors dissipate energy in the same manner as a resistor. If this circuit is driven by an external source at its natural frequency, energy will be added to the system during each cycle. In other words, the circuit will resonate, and exhibit oscillations with large currents.

Construct an AC circuit with a capacitor, and inductor, and an AC current source.

Set the capacitor and the inductance to the values specified by your instructor in the Questions and Answers for Module 5 Discussion Board.

Right-click the power source and set its frequency to a value that is not the resonant frequency of the circuit. Wait at least 2 minutes, and then write down your observations in your laboratory notebook.

Pause the simulation, and reset the AC frequency so that it is equal to the resonant frequency of the circuit. Wait at least 2 minutes, and then describe your observations in your laboratory notebook. Be sure to point out any similarities or differences with the previous step.

Add a resistor to the circuit with very small resistance, R =0.01Ohms. Measure the peak current at frequencies (f) equal to multiples of the resonance frequency. In particular, try frequencies equal to 0.5, 0.75, 0.9., 1.0, 1.1, 1.25, and 1.5 times the resonance frequency (fo).

Use Excel to plot peak current as a function of frequency on a scatter plot. Do not insert a trendline.