Методическая разработка по английскому языку по специальности «Стандартизация, сертификация и метрология» - страница 12

master standard – основной стандарт – негізгі стандарт

fundamental – основной – негізгі, ең бастапқы

technique – метод – техника, әдіс

to disrupt – разрушать, подрывать, искажать – қирату, талқандау, бұзу

Ex.1 read and translate the text

What is standard?

In the science of measurement, a standard is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. Standards are the fundamental reference for a sy stem of weights and measures, against which all other measuring devices are compared. Historical standards for length, volume, and mass were defined by many different authorities, which resulted in confusion and inaccuracy of measurements. Modern measurements are defined in relationship to internationally- standardized reference objects, which are used under carefully controlled laboratory conditions to define the units of length, mass, electrical potential, and other physical quantities.

There is a three-level hierarchy of physical measurement standards. At the top of the tree are the master standards – these are known as primary standards. Primary standards are made to the highest metrological quality and are the realization of their unit of measure. Historically, units of measure were generally defined with reference to unique artifacts which were the legal basis of units of measure. A continuing trend in metrology is to eliminate as many as possible of the artifact standards and instead define practical units of measure in terms of fundamental physical constants, as demonstrated by standardized technique. One advantage of elimination of artifact standards is that intercomparison of artifacts is no longer required. Another advantage would be that the loss or damage of the artifact standards would not disrupt the system of measures.

The next quality standard in the hierarchy is known as a secondary standard. Secondary standards are calibrated with reference to a primary standard.

The third level of standard, a standard which is periodically calibrated against a secondary standard, is known as a working standard. Working standards are used for the calibration of commercial and industrial measurement equipment.

Primary reference standards

Gauge blocks are used as a wo rking standard to check the calibration of measurement tools such as