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- In short the answer is no. What you do need to take into account is the uncertainty of measurement.
- This is used for the coating on radiometers because, when applied in the appropriate manner, it is one of the lowest reflectance surfaces that exist.
- The measurement uncertainties achievable with pressure gauges, particularly traditional circular 'dial' gauges, are often expressed in one of two ways - as a percentage of reading or as a percentage of full-scale reading and the differences can be very significant, particularly when working at pressures much lower than an instrument's full-scale.
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- The diagram below shows the approximate operating ranges of some commonly available pressure and vacuum measuring instruments.
- There is no fixed period for the validity of a calibration certificate - it is not like your cars MOT certificate. However, measurement results stated on certificates are usually 'on the day' values and no allowance is made for subsequent drift.
- The International Prototype Kilogram is not perfectly stable (its mass changes with time), the amount it changes cannot be known perfectly (there is no 'perfect' reference against which to judge it) and the values of the national copies cannot be monitored at the highest level of accuracy without being compared directly with it.
- Calibration is often thought to be expensive but the information contained in the resultant certificate is usually worth considerably more.
- In Europe the weight classification system adopted is that produced by the International Organization of Legal Metrology (OIML), known as document OIML Recommendation R 111.
- The triple point temperature of a pure substance is the unique temperature at which the solid, liquid and vapour phases of the substance co-exist in thermal equilibrium. Such triple points make ideal reference points for the calibration of thermometers.
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- There is no clear boundary between pressure and vacuum and the word vacuum simply refers to part of the pressure scale. Its definition is not precise but it is commonly taken to mean pressures below, and often considerably below, atmospheric pressure.
- Different religions and cultures have their own conventions about the significance of the days of the week, and where in the week the cycle is said to begin. Even in modern times there are variations to accommodate specific needs.
- The international system is a set of seven base units chosen to fulfil the requirements of science and technology. The selection of seven base units is a matter of choice.
- 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.
- Battery powered radio-controlled clocks typically check the time only every hour or two, or even less, This is to conserve the battery.
- Stylus (mechanical contact) and optical (non-contact) instruments operate on different physical principles and will always tend to differ in the results they give for a surface.