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 is shorted, bypassing current around the other elements.
- ✓ The component under test is open, stopping all current flow in the single series path.Correct
- C. The source voltage has increased, raising the drop across the highest-resistance element.
- D. The other components have become shorted, concentrating all voltage on the remaining good component.
Why B is correct
In a series circuit, an open stops all current. With no current flowing, there are no voltage drops across the intact resistors (E = I × R = 0), and by Kirchhoff's voltage law the full source voltage appears across the open component. This is a fundamental troubleshooting principle. (NEETS Mod. 1 §3-2, NEETS Mod. 1 §3-4)