Yes, magnetic fields - and indeed magnetically permeable materials close to a balance - can effect a weighing result.

Mass is therefore a base quantity in the SI and its unit is the kilogram, which is abbreviated to kg.

Thermocouples are the most common sensors in industrial use due to the fact that they are small, simple, rugged and of low cost. They consist of two dissimilar conductors (wires) joined at a junction and contained in an insulator.

Surface temperature is notoriously difficult to measure...

No, they are not. The internationally recognised SI unit for pressure is the pascal, abbreviated to Pa, and this is the unit realised by the primary measurement standards in the world's national metrology institutes to provide traceability for pressure measurements.

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.

Equivalent force values are given here.

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.

Yes, magnetic fields - and indeed magnetically permeable materials close to a balance - can effect a weighing result.

Check plugs and parametric measurements are not mutually exclusive. It is NPL's opinion that for checking master gauges (i.e. not products) both check plugs and parametric measurements have their place.

The Rugby radio station, with call-sign GBR, was brought into service in 1926 by the Post Office as a telegraphy station with world-wide coverage and a frequency of 16 kHz.

Historically there have been a variety of units of mass and density, and approximate conversion factors to some of these are given below.

The answers to some frequently asked questions about length metrology.

To some degree yes. Ideally, the reflectivity of both the reference and test surface should be equal to give maximum contrast fringes.

There are many good books and in addition NPL produces a range of Good Practice Guides relating to dimensional metrology.

No. Since 1983 the metre has been re-defined in terms of the speed of light and is realised using laser wavelengths.