5L20.10 RLC Circuits: Phase Differences In a Series RLC Circuit

PIRA 5L20.10 RLC Circuits: Phase Differences In a Series RLC Circuit

Photo Shows the Demonstration Circuit Used by the University of Texas at Austin.

Instructions / Notes:

Demonstration includes a Series RLC Circuit and a computer on a cart connected to a PASCO interface which has a differential amplifier built into each channel.

Note: It is recommended that you familiarize yourself with operating the software no less than ten to fifteen minutes before the classbreak.

The values for the components on the above circuit board are 1 K ohms for the resistor, 0.1 H for the inductor and 1 microfarad for C.

The above screen shot shows the location of the start icons and the the frequency control icons.

To Begin: Click on the the "Start" icon on the top center of the screen to begin using the PASCO combined signal generator, voltage sensors and interface.

When data is being acquired the green "Start" icon will change to red and say "Stop"

Adjusting the plus, (+) and minus, (-) signs under the frequency read out will change the frequency by 100 Hz each time the (+) or (-) icon is selected.

The first frequency adjustment must be up - or - else you will crash the program, which does not respond well to zero hertz.

At low frequencies X_C shows the occurrance of a series large voltage drops across the capacitor.

Note: the Pasco interface is set up with voltage probes.

Thererfore - no currents are being measured

The voltage drop reading for the inductor at 25 Hz is about 2/10ths of a volt.

Increase the frequency adjuster until it reads 525 Hz

The series RLC circuit is at resonance at 500 Hz. So, 525Hz is off by a bit, but it should show the following:
- X_C and X_L have the same amplitude - but are definitely out of phase relative to each other.
- At resonance the voltage drop across the resistor reaches its maximum value.

For a final data run, adjust the frequence upward until it reads 2,025 Hz

At higher frequencies, the value of X_L increases substancially when compared to the starting point of this demo.

At 2025 Hz - X_C is only showing about a 1/4 volt.

This apparatus is stable only to about 2200 Hz.

So, we recommend to only raise the frequency up to 2,025 Hz.

Last Updated 03/10 - University of Texas at Austin Physics Dept. - All Rights Reserved.