Electricity and Magnetism ** 5L20.19 ** AC Circuits


Phase relationships and resonance in an RLC circuit


Theory: In a series RLC circuit at resonance, the current will be maximized, and in phase with the voltage. At frequencies lower than the resonance frequency, the capacitor tends to dominate and the voltage lags the current; at higher frequencies the inductor tends to dominate and the voltage leads the current.

Description: Use the following settings for C and L: C = 0.04 microfarads; and L = 0.04 H. The resonance frequency is about 1300 Hz. At 1100 Hz the circuit is clearly capacitive, and at 1500 Hz it is clearly inductive. It's also easy to see that the current peaks, and is in phase with the voltage, at resonance.
In a small room, the students can view the scope directly. In a larger room, the video camera can show the scope screen on a TV monitor, or all 6 monitors in room 107.

Setup time: 20 minutes

References: (available in the demo room)