Lab Activity: RC Circuits
If you are taking this course through PA Homeschoolers, you must submit this lab report.
This lab activity is composed of two parts. Both have the goal of investigating the behavior of resistor-capacitor circuits.
Part 1:
Build the circuit shown below using a 9-volt battery, a 20000-Ohm resistor and a 1000-microfarad capacitor.
A. Do not connect to one pole of the battery until you are ready to take measurements. The unconnected wire will act as a switch.
B. Calculate and record the time constant (RC).
C. Use a stopwatch and a multimeter (in voltmeter mode) to record the voltage across the capacitor every 5 seconds after you make the final connection to the battery until the system reaches steady state. Record your results in a data table.
D. Repeat step C, this time measuring the voltage across the resistor.
E. Create two gr aphs. On the first graph show the voltage across the capacitor versus time and on the second graph show voltage across the resistor versus time. Discuss the relationship between the two graphs in the conclusion of your lab report.
IMPORTANT: Make sure that the capacitor is fully discharged before connecting it in the circuit in parts C and D. This can be done by simply connecting a single wire across the capacitor (short-circuit it).
NOTE: If the type of capacitor you use has a positive and a negative side it's called an electrolytic capacitor. The dielectric in such capacitors is very thin, and is created in the manufacturing process by having an insulation layer produced by electrolytic deposition. If the polarity of the capacitor is not connected correctly to the potential difference, the thin layer can be destroyed, allowing conduction through the capacitor (dielectric breakdown) and overheating. So when making your connections, be sure that the positive lead on the capacitor is attached to the high potential and the negative lead is attached to the low potential. In other words, if connecting directly to a battery, the positive side of the capacitor connects to the positive side of the battery. If your capacitor does not have positive and negative markings, then there is no need to worry about this.
Part 2:
Before you do anything else, please work out the answers (by hand) for activity #2 shown below. Then use the simulation shown below to build the circuit and test your answers.
After the simulation opens, choose the RLC option and then build the circuit seen above. Use the simulation meters to measure the answers you previously calculated by hand. If you get different readings than you expect, try to determine why. If you are having a difficult time with activity #2, click here to see the solution. As always, please record all your work in your lab notebook.
Click on the simulation to open it.
