USCG Exam PracticeElectrical measuring devices and instrumentation
When connecting an ammeter to measure current in a circuit, the correct procedure is to connect it:
- A. In parallel across the load, on the highest range first
- ✓ In series with the load, after opening the circuitCorrect
- C. In parallel across the voltage source, observing polarity
- D. In series with the load, using a multiplier resistor to extend range
Why B is correct
An ammeter must be connected in series so all circuit current passes through it; the circuit must be opened to insert it. Its range is extended by a shunt resistor in parallel with the movement, not a multiplier. Connecting an ammeter across a voltage source would drive a destructive short-circuit current through the meter.
Cited:NEETS Mod. 3 §1-2