USCG Exam PracticeElectrical measuring devices and instrumentation
A D'Arsonval meter movement is reading in the lower one-third of its scale. What is the correct action to improve measurement accuracy?
- ✓ Switch to a lower range so the reading falls in the upper two-thirds of the scaleCorrect
- B. Switch to a higher range to prevent movement damage
- C. Short the leads and perform a zero adjustment
- D. Read the scale straight-on to eliminate parallax error
Why A is correct
Meter accuracy is stated as a percentage of full-scale deflection, so readings are most accurate in the upper two-thirds of the scale. Selecting a lower range brings the pointer into that region, improving accuracy. Switching to a higher range would move the pointer even lower on the scale.
Cited:NEETS Mod. 3 §1-1