ARRL Technician Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

When an ohmmeter is connected across an unpowered circuit and initially indicates a low resistance that increases over time, it suggests that a component within the circuit is charging or discharging. A large capacitor in the circuit would be the most likely explanation for this behavior. Initially, the capacitor would allow current to flow, showing low resistance. As time progresses, the capacitor charges, creating an increasing resistance as the meter reads the growing impedance of the charging capacitor until it reaches a fully charged state where the resistance stabilizes.

This phenomenon is particularly relevant with larger capacitors, as they take longer to charge compared to smaller ones. In contrast, a small capacitor would charge more quickly, resulting in a more rapid change in resistance that may not be as easily observed. The other options do not adequately explain the observed behavior of the ohmmeter, as intermittent connections or a failing resistor would not typically exhibit a gradual increase in resistance over time in this manner.