Technician 2026-2030T7D10
What reading indicates that an ohmmeter is connected across a large, discharged capacitor?
A
Answer
Practical circuits, troubleshooting, and measurements
Type
A
Increasing resistance with time
B
Decreasing resistance with time
C
Steady full-scale reading
D
Alternating between open and short circuit
Answer Notes
An ohmmeter works by applying a small voltage from its internal battery to the component being tested and measuring the resulting current flow. When you connect it across a large, discharged capacitor, the capacitor initially acts like a short circuit, allowing a large amount of current to flow. The meter interprets this high current as very low resistance.
As the capacitor begins to charge from the meter's battery, the current flowing into it decreases. The ohmmeter interprets this dropping current as a steadily increasing resistance.
Eventually, when the capacitor is fully charged to the meter's voltage, current stops flowing entirely. At this point, the meter will display infinite resistance (an open circuit). Distractors suggesting decreasing resistance or steady readings fail to account for the charging process.
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Which of the following precautions should be taken when measuring in-circuit resistance with an ohmmeter?