Jawaharlal Nehru Technological University Hyderabad B.Tech IV ELECTRONIC MEASURING INSTRUMENTS Previous Question Paper (July/August - 2022 - R16)

Repeatability is the ability of a measuring instrument to provide the same output reading when the same input is applied repeatedly under identical conditions (same observer, same instrument, same location, and short time interval). It represents the variation in measurements taken by a single instrument over a short period.

Reproducibility is the ability of an instrument to provide the same output reading when the same input is applied under varying conditions, such as different observers, different locations, different methods of measurement, or over a longer period of time. High reproducibility indicates that the measurement process is robust against external environmental or procedural changes.

Static characteristics refer to the performance criteria of an instrument when measuring a quantity that is constant or varies slowly with time. These characteristics define the relationship between the input and output under steady-state conditions.

Key static characteristics include:

• Accuracy: The closeness with which an instrument reading approaches the true value of the quantity being measured.
• Precision: The measure of consistency or reproducibility of a set of measurements. It indicates the degree of agreement between repeated readings.
• Sensitivity: The ratio of the change in output to the change in input, defined as
  S = ΔOutput / ΔInput
  .
• Resolution: The smallest change in the measured quantity to which the instrument can respond.
• Linearity: The ability of the instrument to maintain a direct proportional relationship between input and output over its operating range.
• Hysteresis: The difference in output readings for the same input when approached from increasing versus decreasing directions.
• Drift: A gradual shift in the output reading over time while the input remains constant, often caused by environmental factors like temperature.
• Threshold: The minimum input value required to produce a detectable output change from zero.