Capacitor charging and discharging

Chapter 3.17 Capacitor charging and discharging

Lessons In Electric Circuits Volume VI – Experiments Book
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Lessons In Electric Circuits Volume VI – Experiments Book

  • 138CHAPTER 3. DC CIRCUITS3.17Capacitor charging and dischargingPARTS AND MATERIALS• 6 volt battery• Two large electrolytic capacitors, 1000 µF minimum (Radio Shack catalog # 272-1019,272-1032, or equivalent)• Two 1 kΩ resistors• One toggle switch, SPST (”Single-Pole, Single-Throw”)Large-value capacitors are required for this experiment to produce time constants slowenough to track with a voltmeter and stopwatch. Be warned that most large capacitors are ofthe ”electrolytic” type, and they are polarity sensitive! One terminal of each capacitor shouldbe marked with a definite polarity sign. Usually capacitors of the size specified have a negative(-) marking or series of negative markings pointing toward the negative terminal. Very largecapacitors are often polarity-labeled by a positive (+) marking next to one terminal. Failure toheed proper polarity will almost surely result in capacitor failure, even with a source voltageas low as 6 volts. When electrolytic capacitors fail, they typically explode, spewing causticchemicals and emitting foul odors. Please, try to avoid this!I recommend a household light switch for the ”SPST toggle switch” specified in the partslist.CROSS-REFERENCESLessons In Electric Circuits, Volume 1, chapter 13: ”Capacitors”Lessons In Electric Circuits, Volume 1, chapter 16: ”RC and L/R Time Constants”LEARNING OBJECTIVES• Capacitor charging action• Capacitor discharging action• Time constant calculation• Series and parallel capacitanceSCHEMATIC DIAGRAM