Demonstrativ Watt balansvåg i Lego

Examensarbete på grundnivå
Maskinteknik 180 hp (högskoleingenjör)
Fabian, Weibull
Filip, Persson
The unit kilogram is defined by an artifact, consisting of platinum and iridium. This artifact does only exist in one copy and in addition to this there are forty kilogram prototypes in a number of countries metrology institutes. It has, during a longer time, shown that a few of these prototypes are drifting in weight compared to the original artifact and of this reason there are now a process of establishing a new definition of the kilogram going on which is going to be defined with the help of a so called watt balance after the fact that the Planck constant has been given a fixed value. The purpose of this work has been to build a demonstratively version of a watt balance in Lego, where functions for weighing mass and calculations of Planck’s constant are included. This scale will be used in purpose of education to raise the knowledge of how watt balances works. All work has been conducted at SP Technical Research Institute of Sweden, which is the national metrology institute in Sweden. A metrology institute is the organization responsible for the fundamental SI units in the country. The completed thesis is the build-up of a watt balance in Lego that has gotten the functionality that has been wanted, although with a small systematic fault resulting in a wrongly measured weight. The scale shows the principle of how a measurement with a watt balance is made, with regards to both mass and a calculation of Planck’s constant. As a result of this study, it has shown that it is necessary with thorough work if a high level of accuracy is to be achieved. Good knowledge of the real function in addition to good components is of utmost importance to be able to build a scale with high precision. The results are to be seen as valuable since the functionality is good enough to use in educational purpose. However, the measurement results obtained when weighing is not of high enough precision, this because of the aforementioned systematic fault. The software to control the scale did not need to be created from scratch. Instead, the files for control via LabView are provided by the authors of the report “A LEGO Watt balance: An apparatus to demonstrate the definition of mass based on the new SI”.
Materialvetenskap , Grundläggande vetenskaper , Konstruktionsteknik , Materials Science , Basic Sciences , Construction engineering
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