1 Answers
Option 4 : All of these
All the given static characteristics are desirable.
Accuracy: It is the closeness with which an instrument reading approaches the true value of the quantity being measured. It means conformity to truth.
It can be expressed in the following ways.
Point accuracy: This is accuracy of the instrument only at a point on its scale. It doesn’t given information about the information about the accuracy at any other points on the scale.
Accuracy as percentage of scale range: When an instrument has uniform scale, its accuracy can be expressed in terms of scale range.
Example: The accuracy of a voltmeter having range of 200 V may be expressed as ±1 percent of scale range
±1 percent of scale range = 0.01 × 200 = 2 V, i.e. the reading will have ±2 V error.
Accuracy as percentage of true value: While measuring we can express the accuracy of reading as a percentage of true value.
Example: The accuracy of a voltmeter having full scale range of 200 V and it is used to measure 20 V and the accuracy is ±1 percent of true value
True value = 20 V
±1 percent of true value = 0.01 × 20 = 0.2 V
Sensitivity: It is defined as the ratio of the changes in the output of an instrument to a change in the value of the quantity being measured. It denotes the smallest change in the measured variable to which the instrument responds.
Deflection factor or inverse sensitivity is the reciprocal of sensitivity.
Reproducibility: It is the degree of closeness with which a given value may be repeatedly measured. It may be specified in terms units for a given period. Perfect reproducibility means that the instrument has no drift.