A resistor-capacitor circuit is an electrical system comprising resistors and capacitors. These ‘RC circuits’ are invaluable for filtering signals by blocking certain frequencies, and letting others through. Today we describe a simple experiment to examine what happens when we discharge a capacitor, or allow electric current to flow through a resistor.
Setting Up a Resistor-Capacitor Circuit
This experiment requires a circuit board with a capacitor wired in series with a resistor. The researcher has already worked through different resistance values, and chosen two for the experiment. They have an iPad standing by with an online voltage probe.
They also have batteries connected to the circuit. And a single-pole double-throw switch allowing them to discharge the capacitor via the resistor. They have tested their resistor-capacitor circuit by fully charging the former, so everything is good to go as we enter this video courtesy of Vernier Science Educator.
Observations from the Demonstrator Video
The reading on the online voltage probe dips, when they close the switch to allow the capacitor to discharge. This process takes a little while longer, but they can reverse it by recharging the capacitor with the battery.
Resistance is a measure of how hard it is for electric current to flow through a circuit. Like we said, the researcher has chosen two resistance values so they can compare results. We can clearly see the difference in their video, but what do the shapes of the curves mean?
The researcher obtains the best fit by applying natural exponential analysis. In a natural exponential function, the slope of the tangent line is equal to the height of the curve at that point. So all is logical, as science ought to be, with everything in its place.
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