Metrology

Physical quantity

A physical quantity is defined as a physical property of a body or entity with which it is possible to describe phenomena that can be measured (quantified by measurement). A physical quantity can be expressed as the combination of a magnitude expressed by a number – usually a real number – and a unit of measurement. They …

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Linear Variable Differential Transformer (LVDT)

A linear variable differential transformer (LVDT) is one of the most popular electromechanical devices used to convert small mechanical displacements (mechanical vibrations or mechanical motion of the order of a few millimeters or fractions of a millimeter) into amplified electrical signals (variable electrical current, voltage or electrical signals, and vice versa). LVDTs are linear position sensors. Drive …

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Measurement error

The error of measurement is the difference between a measured value of a quantity and its true value. The term measurement uncertainty is often used as a synonym for measurement error. In metrology, the analysis of errors includes the study of uncertainties in the measurements, since no measure as far as it is carried out with care …

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Measuring instrument

A device used for the measurement of a certain physical quantity is called a measuring instrument. The instruments indicate the value of these quantities, based on which we get some understanding and also take appropriate actions and decisions. Types of measurement instruments There are two main types of measuring instruments: analog and digital. The analog instruments indicate the magnitude of …

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Measurand

The measurand is defined as a physical quantity to be measured (such as length, weight, and angle). The specification of a measurand requires: the knowledge of the species of physical quantity; the description of the state of the phenomenon, of the body or of the substance of which the physical quantity constitutes a property (including all the …

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Fidelity [metrology]

In Metrology, fidelity is defined as the degree to which a measurement instrument indicates changes in the measurand quantity without dynamic error. In metrology, it is said that a measuring instrument is all the more “faithful” the more it provides indications of little discordant value between them in the course of several measurements of a constant physical quantity. …

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Measurement

In Metrology the term measurement is closely associated with all the activities about scientific, industrial, commercial, and human aspects. It is defined as the assignment of a number to a characteristic of an object or event, which can be compared with other objects or events. The knowledge of the reality that surrounds us is based on the …

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Length

The length, quantitatively and objectively, identifies a material body according to a single main or prevalent dimension of the body itself. The measure of length leads to the knowledge of the geometry of bodies, that is to their “dimensions.“ Many length measurements are also based on many (indirect) measurements of other physical quantities. Length measurements can be obtained …

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Pous

The pous (plural podes; from Greek: ποῦς, poûs) or Greek foot (plural feet) was a Greek unit of length.