The GATE Grind

GATE 2025 IN – Question 23

Measurements · Errors and uncertainty · 1 mark · Multiple choice

A $3\tfrac12$-digit digital voltmeter has specified accuracy $\pm(0.5\%+1)$. If it measures 10 V DC, the error would be ______. Accuracy is expressed as $\pm(\%\text{ of reading}+\text{digit})$.

  1. $\pm0.4\%$
  2. $\pm1.5\%$
  3. $\pm0.6\%$
  4. $\pm1\%$

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Correct answer: (C) $\pm0.6\%$

Explanation

Using the intended 20 V range of a $3\tfrac12$-digit meter, one least-significant count is 0.01 V.

The range is implicit in the source question.

The error bound is $0.005(10)+0.01=0.06$ V.

Relative error is $(0.06/10)100\%=0.6\%$.

Select **C**.