Difficulty: Easy
Correct Answer: Correct
Explanation:
Introduction / Context:
Technicians often need a quick field test to identify gross capacitor faults without a dedicated LCR meter. An ohmmeter cannot report capacitance value directly, but it can still reveal shorts, opens, or severe leakage by observing the time-varying resistance as the capacitor charges from the meter's internal source.
Given Data / Assumptions:
Concept / Approach:
When connected, a healthy capacitor initially appears as a low resistance (inrush as it charges) and then the indicated resistance rises toward a high value as the charge current decays. A shorted capacitor reads near-zero resistance and stays there; an open capacitor shows no charging action (reading may remain infinite). Excessive leakage yields a steady mid-range resistance. Thus an ohmmeter provides a practical go/no-go assessment.
Step-by-Step Solution:
Verification / Alternative check:
Technician guides describe this classic method; bench LCR readings can confirm findings. Oscilloscope with a known resistor can also time the charge curve (V(t) = V_s * (1 − e^(−t/RC))).
Why Other Options Are Wrong:
Incorrect: discards a widely used diagnostic technique.
Only true for electrolytics / above 1 μF: the behavior occurs for any capacitor; larger C simply makes the effect more visible on slow meters.
Common Pitfalls:
Failing to discharge first; reversing polarity on electrolytics; concluding “bad” solely from a fast change on a digital meter with autoranging.
Final Answer:
Correct
Discussion & Comments