Facebook
Google
GitHub
LinkedinDC Electric Circuits
Capacitors
15 questions By Tony R. Kuphaldt
-
Question 10 of 15
Calculate the total capacitance in this collection of capacitors, as measured between the two wires:
Reveal answer132.998 pF
Follow-up question: suppose one of the terminal block’s hold-down screws were to come loose on one of the leads for the middle capacitor, making a bad (open) connection. What effect would this have on the total capacitance?
Notes:It is most helpful to first draw a schematic diagram for this capacitor network before trying to perform any capacitance calculations, in order that a clear understanding of the series/parallel connections be established.
-
Question 11 of 15
Identify the following capacitor values and styles:
Reveal answer
Notes:Ask your students how they can tell whether a capacitor’s value is given in microfarads or picofarads. There is a way, even if the metric prefix is not printed on the capacitor!
-
Question 12 of 15
When checked with an ohmmeter, how should a properly functioning capacitor respond?
Reveal answerA “healthy” capacitor should register as an open circuit between its terminals, after the initial charging period.
Follow-up question: what do you suppose is the most likely failure “mode” of a capacitor, open or shorted? Explain your answer.
Notes:Have your students actually test a few capacitors with their ohmmeters in class. For large capacitor values, the charging time may be substantial! Students need to be aware of this, and the effect it has on the ohmmeter’s indication.
Although an ohmmeter check of a capacitor is not a comprehensive analysis, it is certainly better than nothing, and will detect the more common faults.
