Static And Dynamic Characteristics of Measuring Instruments


Precision is a measurement of how close a series of measurements(different samples) are to one another, irrespective of the actual/true value.

You can evaluate the precision of measurement by comparing two or more repeated values of measurement.

For example: if you measure your height 4 times and get 6′ 1” each time then your measurement is very precise.


Accuracy is the evaluation of how close a measured quantity comes to the actual or true value.

To evaluate the accuracy of a measurement, the measured value must be compared to the true or standard value.

For example: if you know your actual height is exactly 6’1” and you measure your height 6’1” again with a measuring tape then your measurement is accurate.


Sensitivity is the smallest absolute amount of change that can be detected by measurement within a given resolution. It is often expressed in terms of millivolts, micro ohms or 10th of a degree.

For example: For a voltmeter that ranges between 0-15 volt with 5 divisions in a single reading (0-5 volt) will have a sensitivity of 0.5 volts.

Volt Meter
Volt Meter


Repeatability is the variation in measurements obtained when one person measures the same unit (test material) with the same method on the same condition in a short period of time.


The proximity between the results of measurement when a particular test material is measured by different personnel with different methods using distinct instruments under various conditions, location and times is known as Reproducibility.


Calibration is the process of evaluating and adjusting the precision and accuracy of the measuring instrument by comparing it with known standard measurement.


Interchangeability is the condition when one part or component get assemble perfectly with the other one while both are selected randomly, satisfying the functionality of the assembled good.

Interchangeability is possible when certain standards are followed like having a similar drawing for a particular component.

For example: If any two random holes and shaft fit perfectly.


The electronic method of magnification that is ideally suitable for the processing of signals is called amplification.

For example, a Lower voltage signal can be amplified to a higher voltage signal.
Similarly, ambiguous or disturb sound waves can be amplified to clear sound wave using the amplification method.

Example of Amplification.
Example of Amplification.


Magnification is the process of enlarging something only in appearance not in physical size so that it is more readable.

Magnification Of Stamp With The Help Of Magnifying Glass
Magnification Of Stamp With The Help Of Magnifying Glass


Drift is an undesirable gradual deviation of the instrument output over a period of time caused by wear and tear and high stress over some parts.


Resolution is the ability of an instrument to read the smallest dimension of measurement. The higher the resolution, the smaller the measurement it can measure.


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