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- A platinum resistance thermometer (PRT) is a device which determines the temperature by measuring the electrical resistance of a piece of pure platinum wire.
- In 1799 it was agreed that the unit should be the mass of one cubic decimetre of water at a temperature of 4 °C, which would be called a kilogram (kg). The mass of one cubic centimetre of water would be called a gram (g).
- The ITS-90 (International Temperature Scale of 1990) defines procedures by which certain practical thermometers of the required quality and precision can be calibrated in such a way that the values obtained from them can be precise and reproducible, while at the same time representing the corresponding thermodynamic temperatures as closely as possible.
- The measurement uncertainties associated with specifications for force-measuring devices are often expressed as a percentage of full-scale reading. This is not always the case, however, and sometimes percentage of reading is used instead and the differences can be very significant, particularly when measuring forces that are quite small for a particular instrument.
- There are many different types of barometer but they fit into two broad categories - those containing mercury and those that do not.
- When comparing weights of dissimilar materials the effect of air buoyancy becomes more significant and must be applied even for routine calibrations when true mass values are being determined.
- Transducers are voltage-output devices that can be used with simple signal conditioning but are more sensitive to electromagnetic interference. Transmitters are current-output devices and may have two or three wires.
- The complete inspection by direct measurement of parallel screw threads necessitates the measurement of the effective diameter which, in the case of external threads, is obtained by measurement across cylinders placed in the threads on either side of the screw.
- The MSF h.f. services on 2.5, 5 and 10 MHz ceased at the end of February 1988 as they were of little use nationally, and more accurate methods were available for long-range comparisons.
- Yes, the Measurement of Surface Texture using Stylus Instruments, Guide No 37.
All FAQs
- The density of a solid or liquid may be fundamentally determined by hydrostatic weighing using Archimedes' principle.
- When comparing weights of dissimilar materials the effect of air buoyancy becomes more significant and must be applied even for routine calibrations when true mass values are being determined.
- It depends on the job at hand. However, you should have at least ...
- There are many types of force transducer and they are used with instrumentation of varying complexity. In designing or specifying a force measurement system for an application, it is useful to understand the basic operation of the transducer to be used and also their broad operating characteristics.
- Some barometer measurement principles are listed below; there are bound to be others.
- For the last 20 years there has been a considerable amount of work undertaken looking for an alternative, more fundamental, definition for the SI unit of mass - the kilogram.
- The recommended values of the fundamental constants are produced by the CODATA Task Group on Fundamental Constants the most recent evaluation was in 1998.
- The frequency with which calibrations should be carried out is an important, if sometimes difficult, question; there is no hard and fast rule but there are two main considerations.
- As infrequently as possible.
- We would recommend that reference flats in interferometers be recalibrated every three to five years depending upon the precision of measurement required.