USCG Exam PracticeElectrical measuring devices and instrumentation
When reading an analog meter, selecting a range that places the pointer in the lower one-third of the scale will:
- A. Improve accuracy because the scale divisions are more widely spaced at the low end
- ✓ Reduce accuracy because meter accuracy is stated as a percentage of full-scale deflection, making the absolute error large relative to the readingCorrect
- C. Have no effect on accuracy since analog meters are linear across the full scale
- D. Protect the movement from overload by keeping deflection low
Why B is correct
Analog meter accuracy is expressed as a percentage of full-scale deflection. A reading in the lower third of the scale represents a small fraction of full scale, so the fixed percentage error is large relative to the indicated value. Readings are most accurate in the upper two-thirds of the scale.
Cited:NEETS Mod. 3 §1-1