Tool Set

 Measurement, the process of combining numbers with physical quantities and phenomena. For science, measurement is indispensable; in engineering, construction and other technical fields; and for almost all daily activities. For this reason, the elements, conditions, limits and theoretical principles of measurement are examined in detail. Also see measurement systems to compare different systems and their development history.

Measurement begins with a definition of the quantity to be measured and always includes a comparison with a known quantity of the same species. If the object to be measured or the size to be measured is not available for direct comparison, it must be converted or "converted" into a similar measurement signal. Since there is always an interaction between the object and the observer or the observing instrument during a measurement, there is always an exchange of energy, which is not significant in everyday applications, but can be significant in some types of measurements and thus limits accuracy.

Measurements can be carried out without tool set the aid of the human senses, often referred to as approximations, or more often with instruments, the complexity of which can range from simple rules for measuring length to sophisticated systems for detecting and measuring quantities that are entirely out of reach. the limits of the range of measurements beyond the capabilities of the senses, such as radio waves from distant stars or the magnetic moments of subatomic particles.

In general, a measurement system consists of a number of functional elements. An element is needed to distinguish objects and to sense their size or frequency. This information is then transmitted via physical signals throughout the system. If the object itself is active, e.g. B. water jet, can power the signal; when passive, it must activate the signal, either by interacting with an energy probe, such as a light source or x-ray tube, or with a carrier signal. Finally, the physical signal is compared with a reference signal of known magnitude, which is divided or multiplied to fit the required measurement range. The reference signal is extracted from the object in a certain amount through a process called calibration. Comparison can be an analog process in which signals are brought to equality in continuous dimensions. An alternative comparison method is quantization by counting, i.e. dividing the signal into equal parts of known size and adding the number of parts.