Diagnosing an open (failed) capacitor using an analog ohmmeter: what needle behavior should you expect?

Introduction:Using an analog ohmmeter to assess capacitors relies on observing transient charging behavior. A healthy capacitor briefly conducts as it charges from the meter's internal battery, then its indicated resistance rises. An open capacitor behaves differently. This question targets practical troubleshooting skills.

Given Data / Assumptions:

• Analog ohmmeter with internal DC source.
• Capacitor disconnected from circuit and discharged before testing.
• Looking for qualitative needle movement.

Concept / Approach:A good capacitor initially appears as a low resistance (charging current flows) and then the resistance increases as the capacitor voltage builds, approaching infinity when fully charged. An open capacitor has a broken internal connection, so no charging current flows and the meter reads open circuit constantly.

Step-by-Step Solution:

Verification / Alternative check:Cross-check with a capacitance meter or ESR meter. An open capacitor will show extremely low capacitance (near zero) and often infinite ESR.

Why Other Options Are Wrong:

• Stay on zero: Indicates a shorted capacitor, not open.
• Move from zero to infinity: Describes a healthy capacitor's transient response.
• Move from infinity to zero: Suggests a short developing; not open.

Common Pitfalls:Failing to discharge the capacitor before testing, misinterpreting the analog scale, or testing in-circuit where parallel paths can mask the result.

Final Answer:Stay on infinity (open circuit).