Home › MCQs › Electronics Engineering › Question #11693
Back to Questions
Electronics Engineering QUESTION #11693
Question 1
When testing a capacitor with a digital multimeter set to capacitance mode, the reading fluctuates wildly and never stabilises. The most likely cause is:
  • The capacitor is within tolerance
  • The capacitor has excessive equivalent series resistance (ESR)✔️
  • The capacitor is open-circuited
  • The capacitor value exceeds the meter range
Correct Answer Explanation
Unstable, fluctuating capacitance readings are a classic symptom of high ESR in an electrolytic capacitor. High ESR is caused by dried-out or degraded electrolyte, corrosion, or age. A dedicated ESR meter gives a more definitive diagnosis. An open capacitor reads OL (overload); an in-range good cap gives a stable reading.