When a voltage of 200 V is measured by a voltmeter, five successive readings are obtained as 204 V, 205 V, 203 V, 205 V and 203 V. The percentage accuracy and precision are ___________.

Concept

The accuracy of voltmeter is given by:

% Accuracy = \({V_{mean}-V_{true}\over V_{true}}\times 100\)

\(V_{mean}={V_1+V_2.........V_N\over N}\)

Precision is based on the deviation of readings from the mean and is given by:

\(Precision={Max \space Deviation \space from \space Mean\over V_{mean}}\)

Calculation

Given readings are 204 V, 205 V, 203 V, 205 V and 203 V

\(V_{mean}={204+205+203+205+203\over 5}=204\space V\)

% Accuracy = \({204-200\over 200}\times 100\)

% Accuracy = 2.5%

Mean = 204 V 

Maximum deviation from mean = 204 - 203 = 1V

\(Precision={1\over 204}\times 100\)

Precision = 0.5%