# Tag Info

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as a metrologist, I wouldn't do that. Not because is not right, but because you could be undestimating your instrument's uncertainty. Usually what we metrologists do is take the greatest uncertainty, for the maximum entropy principle, because there's nothing more wrong than underestimating your unc

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So long as all the other values are still in SI units, things should work as you expect. That is because mass in kg is precisely equal to mass in grams divided by 1000. But note that if you use grams for all the other units i.e. density $\rho$ in grams/m^3 or grams/cm^3, then you will have to appropriately scale for those changes in units as well.

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Prof. Walter Lewin is correct. Kirchhoff's Voltage Law holds only when the voltage source is inside and part of the current circuit. Even in a transformer circuit the secondary coil of the transformer acts as the connected voltage source of the components circuit connected to the secondary. Dr. Lewin's explanation https://www.youtube.com/watch?v=LzT_YZ0xCFY ...

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Generally neutron detectors are built around detection of nuclear reactions that occur in the presence of neutron radiation. For a simple example, if helium-3 is exposed to thermal neutrons, it tends to interact like: $$\rm ^3He + n\to {^3H}+{^1H}$$ producing a proton and a tritium nucleus, both of which are created with a fair amount of energy and thus ...

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As far as I know, you only know the location an electron is when it interacts with something else. If you know where the other thing was, then you know where the electron was. The other thing might be the the element in a charge coupled device, an ionize gas molecule in a cathode ray tube, a droplet in a cloud chamber, or an ion on a photographic plate.

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$\phi (A)$ is by definition just $<A|\phi>$, for some operator A. Using completness property for position operators $\int dx\, |x><x| = 1$, we arrive at $\phi(A) = \int dx <A|x>\, <x|\phi>$. Now, since $<a|b> = <b|a>^*$ we see that this is simply $\phi(A) = \int dx <x|A>^* \phi(x)$. This is the main idea. You ...

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If a piece has chipped off, you should be OK. You might smooth any sharp edges with fine sandpaper. If there is a crack, you might have trouble in the future. Cracks can grow. It should not affect alignment, so long as you can fasten it down as usual. But you will find out soon enough if you try it and it doesn't work.

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Wouldn't their absorption and emissions be redshifted and blueshifted by the motion? The motion is perpendicular to the microwave cavity, so large Doppler shifts are not observed relative to that direction due to the tossing up of atoms. Although, the velocity always has some uncertainty both perpendicular and parallel to the cavity, and the angle of the ...

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Say the original signal is $y$ with noise spectrum $s(f)$. Let $A$ be the gain of an amplifier, and let $z(f)$ be the noise introduced by the amplifier at the output. A d.c. amplifier of gain $A_{dc}$ would produce at its output approximately $$A_{dc} (y + s(0)) + z(0).$$ There is more than one way to modulate the signal so as to use a lock-in amplifier. ...

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The uncertainty of the fit parameters is specific to the used fitting model. So the question is not, which uncertainty is correct, but which model should be used. In statistics there are tools for model selection (e.g. cross-validation, penalties for each fit-parameter), as well as for "data point selection for fits". I reckon the data point ...

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The answer lies in the scientific goals of the mission. You can find these in the LISA Science Requirements Document. The so called roll-off is a relaxation of the requirements as the lower frequencies.

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Once you set the origin as a data point without any error, ie the best fit graph must go through through the origin you limit the number of possible lines that fit the data as compared with the more general case of assuming it to be a linear relationship. One thing which is not immediately obvious from your graph is that the lowest value data point is a long ...

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I think the answer was more simple than I anticipated. The point is that in to enable 3D Anderson localization of light, the strength of disorder must be larger than some critical value. This has limited the current search to materials with large refractive indexes, such as powdered GaAs, GaP, TiO2 etc, which all have exhibited absorption, fluorescence, and ...

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I recommend Max Jammer, The conceptual development of quantum mechanics, McGraw-Hill; 1966. The book is somewhat old but many of the pioneers of quantum mechanics were still alive or had just recently passed away at the time of the writing, so that Jammer had access to primary sources, sometimes even interviewing key figures. Of course it does suffer from ...

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Although dipoles are very popular in EM theory and are well understood by antenna engineers, they are just one of an infinite set of radiating structures. any structure that contains accelerating coulomb charges will radiate. Where and when the conditions that define plane waves occurs is complex and requires a solid knowledge of modern EM theory derived ...

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There is nothing magic about accelerometers that changes the way a Fourier transform works. If you’re murky on FFTs, I suggest you create some “fake data” that is the sum of one or more pure sine waves, feed it through your analyzer to see what its power spectrum looks like, and run the power spectrum through an inverse FFT (which is secretly the same as an ...

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A substantial observable characteristic of a particle is what it interacts with/can decay into. Carroll of course takes a materialist viewpoint here where particles that "support psychic phenomena" should be able to interact with our brain (or body) matter at ordinary, every-day energy levels. But our meat consists of protons, neutrons and ...

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In my lab course, we use optical equipment provided by Pasco. The diffraction slits you refer to can be found e.g. here. As a caveat, the listed price is specifically for educators; you would have to speak with their sales department to see if the price is different for hobbyists.

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The method that you have used to account for zero error in screw gauge makes no sense for screw gauge zero error. When the reading on the circular scale across the linear scale is more than zero (or positive), the instrument has a positive zero error as shown in case 1. When the reading of the circular scale across the linear scale is less than zero (or ...

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Every precision measurement of the moon's orbital dynamics uses that relationship. If it were wrong, so would be those measurements.

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The underlying assumption here is that chronometer is accurate (it measures time correctly over a sufficiently long interval) but not very precise (it cannot measure intervals of less than 0.1 seconds). Another way of putting this is that the observational errors made when the chronometer is used to measure intervals are random errors, rather than systemic ...

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Suppose I want to know how many people visit a grocery store in a month. Here's one approach: I know that the store is scheduled to be open for 3600 minutes every month, so I can watch the door for one minute and extrapolate. That's a terrible way to extrapolate, because the interval is too small. I might look for a minute where nobody comes, and extrapolate ...

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The measurements shown in this paper are made by shining a tightly focused laser beam onto a cloud of Sr atoms, where the cloud has a vertical size of about 1 mm. This allows comparing the frequency of the clock transition between different parts of the cloud. Figure 3 shows a plot of the measured frequency shift over the vertical extent of the atom sample. ...

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A graph of the number of unstable nuclei of a particular type, $N(t)$ against time $t$ with be an exponential curve $N(t)=N_0 e^{-\lambda t}$ with a gradient at any time $t$, $\dfrac{dN}{dt} = - \lambda N(t)$. If the number of unstable nuclei at time $t_1$ is $N_1$ the number of unstable nuclei at time $t_2$ is $N_2$ then $\Delta N = N_2-N_1$ and \$\Delta t ...

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The reason for using these gases is that they are monoatomic. These gases are in the group of noble gases, so they provide an environment with the least reaction for testing, but what is the reason for using mercury? Mercury, although a liquid metal, but in the gas phase behaves like the same monoatomic gases.

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