An experiment on the variables and constants of the capacitor

Draw up a table and help students to complete it. We did four trials using different capacitors and resistances, but I will only use one as an example to get the idea of what we did across.

To figure out what might be causing this discrepancy I have looked at if any possible error involved in measuring R or C could make the graph be off so much. Failure to heed proper polarity will almost surely result in capacitor failure, even with a source voltage as low as 6 volts.

Deriving exponential equations 30 minutes Worked example: Slow charge and discharge Word, 31 KB Discussion: For the three other trials we did another single capacitor, two capacitors in series, and two capacitors in parallelwe have the same issue.

To provide for some control data and to allow for comparison, a 10 W resistor was used to collect one set of 1V results. Record this information in Data Table 1 on the worksheet. Note that in all of the above graphs, the data is plotted using linear axes, and the best fit lines were Excel-fitted exponential trendlines.

To determine the time constant indicated by our data, we then changed the capacitance C to change the time constant until the curve mapped to the data points. Some students will need help with using the ex function on their calculators. Using this tool, determine and record the starting time i.

When the switch is in position A, the capacitor C gains a charge Qo so that the pd across the capacitor Vo equals the battery emf. R-C circuits and other systems Episode Close examination of the data indicates that 1V is roughly the limit at which the lamp behaved exponentially; while the voltage is greater than 1V the lamp would be emitting light that is, it would be hot.

The wave generator was set to produce square waves and cause the capacitor to charge and discharge constantly. Slow charge and discharge Word, 31 KB Discussion: The other components in the circuit were the voltage source, a digital multimeter DMMa chart recorder, the filament lamp, and a two-way switch.

All start at a point on the y-axis, and are asymptotic on the t-axis. If a datalogger is available, this can be done quickly and can include some rapid decays.

One source of random errors is the limit of accuracy of the chart recorder. Ask your TA to check your data and calculations before proceeding. Instead of reading 1V, 2V, 3V, 4V and 5V consecutively in series, the voltages were set in a shuttling fashion: Back to reality 10 minutes Student experiment: Consider the circuit shown: Students should see that this will result in quantities which get gradually smaller and smaller, but which never reach zero.

This may have introduced some variation of the resistance of the wires. Furthermore, to reduce the error in the data collected, the voltages selected were staggered. Netlist make a text file containing the following text, verbatim: Practice with equations 30 minutes Discussion: All have the same general shape.

Students should see that this will result in quantities which get gradually smaller and smaller, but which never reach zero. The resistance R and capacitance C was measured using an multimeter, where R was measured on the ohmmeter setting and the capacitance was measured by first discharging it and then inserting it into slits in the multimeter for this specific use and using the capacitance setting.

Even though some specifications require the use of data logging for this, it is worth collecting data manually from a slow discharge and then getting the students to plot the graphs of current against time and voltage against time for the decay.

The procedure entailed using a wave generator and an oscilloscope to graph the charging and discharging patterns of the capacitor.difference (from the previous parts) across the capacitor, calculate the theoretical value of the time constant for the black (C=µF) capacitor and then determine the experimental value of the time constant.

Goal of this experiment A capacitor is charged and discharged through a resistor R. Voltage across the capacitor and the current through the resistor are monitored as function of time for two di erent RCtime constants. In this experiment a (computer-emulated) oscilloscope will be used to monitor the potential difference, and thus, indirectly, the charge on a capacitor. The voltage measurements will be used in two different ways to compute the time constant of the circuit. Goal of this experiment A capacitor is charged and discharged through a resistor R. Voltage across the capacitor and the current through the resistor are monitored as function of time for two di erent RCtime constants.

Large-value capacitors are required for this experiment to produce time constants slow enough to track with a voltmeter and stopwatch. Be warned that most large capacitors are of the “electrolytic” type, and they are polarity sensitive! One terminal of each capacitor should be marked with a. 1 Experiment #9: RC and LR Circuits—Time Constants Purpose: To study the charging and discharging of capacitors in RC circuits and the growth and decay of current in LR circuits. Part 1—Charging RC Circuits Discussion: A capacitor stores .

An experiment on the variables and constants of the capacitor
Rated 3/5 based on 10 review