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Is there an official list of independent units of measurements? – When I say 'independent units', I mean those which cannot be broken down anymore, and simultaneously forms the basis for any more, complex measurements. It depends a bit on what you mean by broken down: You could theoretically define all units on the basis of counting elementary ...


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The concept you are looking for is called "dimensionality," which was a concept first coined in 1822. The simplest way of thinking of dimensionalities is that you cannot add two values unless their dimensionalities are the same. Thus, if we think in terms of units, 1 foot + 1 meter is a valid addition statement. This is because both foot and meter are ...


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Physics is not a bureaucracy, so there are no "official" documents like that. There are people called "metrologists" who think all week long about how to make physical standards more precise and they do have fairly well thought out ideas with what physical effects one should start to make precise measurements. These are not necessarily the standards that one ...


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Both are correct. It is a matter of personal preference which you decide to use. It makes the graph easier to understand if axes are labelled in small numbers; it also makes the graph less cluttered. So either you would label the x axis "Pressure in units of 10^6 Pa" or "Pressure in MPa". Labelling the x axis as "Pressure in Pa" and using marker values ...


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You're correct and the video is mistaken. In fact, if cesium atoms were constantly oscillating between the two hyperfine states, cesium beam clocks wouldn't work at all! In its simplest form, a cesium beam clock uses a magnet to separate a stream of atoms into two streams based on their hyperfine state; one state is selected to continue down the tube to be ...


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Yes, they really are oscillating between two different states (not simply driven in one direction), but as you suspect they are not oscillating at the reference frequency. Rather than "just" sending radiation at the atoms to absorb, they also interact with an oscillating magnetic field (which is at the reference frequency). This field spurs some of the ...


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The definition for the cesium clock is: 9192631770 cycles per second is frequency of the radio waves which cause maximum resonance, a physically measurable condition, in the cesium atoms. This corresponds to a particular tuning of the radio. Keeping it tuned provides the reference frequency cited.


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Of course, you can do it with Matlab, Mupad, Maple, Mathematica or even the Smart Math Calculator. Use this method: First define your variables with your units of choice, then tell the programm what the conversion factors from the given units to the target units are, for example, if you have km/h and need m/sec define 1km as 1000m and 1sec as h as 60² ...



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