USCG Exam PracticeDC circuits and electronic principles
A technician is troubleshooting a series circuit and measures the full source voltage across one component while all other components read zero volts. What condition does this indicate?
- A. The component under test has shorted, dropping all voltage across itself.
- ✓ The component under test is open, and no current is flowing in the circuit.Correct
- C. The source voltage has increased, causing an uneven voltage distribution.
- D. The remaining components have all shorted, leaving only the test component with resistance.
Why B is correct
When a component in a series circuit opens, current ceases throughout the entire loop. With no current flowing, there are no voltage drops across the intact resistors (I × R = 0), so the full source voltage appears across the open component. (NEETS Mod. 1 §3-2, NEETS Mod. 1 §3-4)