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, bypassing all other resistances.
- ✓ The component under test is open, stopping all current flow in the circuit.Correct
- C. The source voltage has increased, causing the single component to absorb all power.
- D. The remaining components are wired in parallel with the source, reading zero because they are bypassed.
Why B is correct
When a component in a series path opens, current drops to zero throughout the circuit. With no current flowing, there are no voltage drops across the good components (I × R = 0), and by Kirchhoff's voltage law the full source voltage appears across the open. (NEETS Mod. 1 §3-2, NEETS Mod. 1 §3-4)