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In the past, a common time measuring instrument was the sundial. Today, the usual measuring instruments for time are clocks and watches. For highly accurate measurement of time an atomic clock is used. Stopwatches are also used to measure time in some sports.
Time metrology or time and frequency metrology is the application of metrology for timekeeping, including frequency stability. [ 28 ] [ 29 ] Its main tasks are the realization of the second as the SI unit of measurement for time and the establishment of time standards and frequency standards as well as their dissemination .
C. Calo tester; Calorimeter; Cam plastometer; Cap torque tester; Capacitance meter; Capacitance probe; Capacitive displacement sensor; Cascade impactor; Chemical field-effect transistor
The following is a topical outline of the English language Wikipedia articles on the topic of metrology and measurement. Metrology is the science of measurement and its application. Metrology is the science of measurement and its application.
The idea of using atomic transitions to measure time was first suggested by the British scientist Lord Kelvin in 1879, [204] although it was only in the 1930s with the development of magnetic resonance that there was a practical method for measuring time in this way. [205] A prototype ammonia maser device was built in 1948 at NIST. Although ...
The Jiffy is the amount of time light takes to travel one femtometre (about the diameter of a nucleon). The Planck time is the time that light takes to travel one Planck length. The TU (for time unit) is a unit of time defined as 1024 μs for use in engineering. The svedberg is a time unit used for sedimentation rates (usually
Measuring instruments (50 C, 375 P) M. Measurements and definitions of poverty (3 C, 35 P, 1 F) ... Time deviation; Tree crown measurement; Tree girth measurement;
Doppler instruments are more common. An instrument of this type is the Acoustic Doppler current profiler (ADCP), which measures the water current velocities over a depth range using the Doppler effect of sound waves scattered back from particles within the water column. The ADCPs use the traveling time of the sound to determine the position of ...