Question

Accuracy is specified as 0.5% of the true value. At 5% of full scale, error of the instrument will be:

• A. $\pm 0.025%$
• B. $\pm 0.5%$
• C. $\pm 0.05%$
• D. $\pm 2.5%$

Hint:

When operating far below full scale, the relative error increases significantly.

Answer 1

The Correct Option is D

Step 1: Define Accuracy.
Accuracy is defined as error expressed as a percentage of the true value.

Step 2: Perform Calculation.
Given an accuracy of $0.5%$ of full scale, and a reading of $5%$ of full scale: \[\text{Relative error} = \frac{0.5}{5} \times 100 = 10%\] This indicates an instrument error of $\pm 2.5%$ relative to the measured value.

Step 3: State Conclusion.
The correct option is (D).