FAQs
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Random FAQs
- Instrument calibration is often thought to be expensive but the information contained in the resultant certificate is usually worth considerably more. This is not always appreciated and, on receipt, many certificates are wastefully consigned to drawers, shelves or even wall plaques.
- 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.
- Certified Reference Materials (e.g. Primary Reference Gas Mixtures) produced by NPL under ISO Guide 34 will have an expiry date stated on the certificate.
- These can be downloaded...
- Flyers are available for download or you can contact us.
- A thermistor is simply an electrical resistor whose resistance changes rapidly with temperature.
- Yes, 2000 was a leap year. Since 1752, in this country, years exactly divisible by 100 are only leap years when they are also exactly divisible by 400.
- Fundamentally, temperature is the potential for heat transfer. Thus an object at a higher temperature will lose heat to an object at a lower temperature when they are placed in contact.
- Mass is therefore a base quantity in the SI and its unit is the kilogram, which is abbreviated to kg.
- Battery powered radio-controlled clocks typically check the time only every hour or two, or even less, This is to conserve the battery.
All FAQs
- Formulae are given in Elastic Compression of Spheres and Cylinders at Point and Line Contact by M J Puttock and E G Thwaite.
- Equivalent force values are given here.
- The relationship between the kilogram and the pound is defined exactly as: 1 lb = 0.453 592 37 kg.
- Dew point (or dew-point temperature) is the temperature at which dew, or condensation, forms, on cooling a gas. Where the condensate is ice, this is known as frost point.
- The conventional mass value of an artefact can be calculated from its true mass value using the following equation.
- To convert one non-pascal pressure unit to an alternative non-pascal unit, multiply the 'starting' pressure value by the 'number of pascals' shown against its unit and then divide the product by the number of pascals shown against the second unit.
- To correct a length you need to calculate the difference in temperature multiplied by the product of the length and the expansion coefficient.
- MOY/SCMI specifications are available on the NPL Length website.
- The micrometre (0.001 mm) gauge should be taken first, followed by the hundredth, tenth and millimetre gauges.
- Following these steps ...