# Questions tagged [measurements]

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775 questions
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### Measure mass of an object only using gravitational force

Most if not all of our everyday methods of determining mass / weight work on the principle of normal force. The push provided to you by the surface which allows to sit/stand/lie down over it.The ...
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### Problem of measuring barrier potential by a voltmeter

I have read in my book that The barrier potential of a diode junction cannot be measured by a voltmeter only. It says that the thermal equilibrium is disrupted. Besides , the contact potential is also ...
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### What do clocks measure?

I recently asked a question about the measurement of time, and it has become apparent that I'm really asking a set of related questions, the premises of which need to be shored up and articulated ...
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### Error regions in a simplistic measurement

Suppose I measure two certain parameters, $a$ and $b$, in an object $O$ for two instances. My measurements are Instance 1----> $a=1.4$, $b=1.4$ Instance 2---->$a=1.5$, $b=1.4$ Can, I say, hence for ...
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### Probability of obtaining general quantum measurement outcome

The Fundamental Theorem of Quantum Measurement is stated as follows: Every set of operators $\{ A_n \}$ $n =1,...,N$ that satisfies $\sum_n A_n^{\dagger}A_n = I$ describes a possible measurement on a ...
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### What is a destructive measurement?

What are destructive measurements or incomplete measurements, and what is the (conceptual) difference between them and a usual measurement? I read somewhere that destructive measurements consume ...
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### Toy model for entangling interaction?

Most of the time entanglement is described using some instantaneous classical measurement from an apparatus, but it is possible to describe it between two quantum systems, with two systems $O$ (for ...
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### How can energy in Ev of particles e.g. muons be measured in a cloud chamber?

I have a Wilson thermoelectric cloud chamber and would like to obtaine the energy of cosmic particles e.g. muons. I would greatly appreciate your answer.
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### Maximum Uncertainty of a Measurement?

I know the state of a system at a time T1, and perform a measurement at a later time T2. My question is this: is there a maximum uncertainty on what state I could expect to measure the system? Of ...
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### Quantum measurements

I am reading the paper "Unconditionaly verifiable blind computation". It says at p.9: a measurement in the $\lbrace \vert +_{\phi_i^{\prime}}\rangle, \vert -_{\phi_i^{\prime}} \rangle\rbrace$ ...
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### Determining the value of Pi empirically [closed]

A shower thought hit me so hard I had to come here and ask: Outside pure mathematics, where should I look, if I wanted to physically measure the best possible approximation for $\pi$? How many ...
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### What type of time dependent measurement would be the same whole over the world?

What type of periodic measurement would be the same all over the world at the same time? What I mean is there a phenomena that is observed similarly all over the world at the same moment. A ...
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Let's say I have a wavefunction $\Psi$ which can be decomposed into a sum of it's energy eigenstates: $$\Psi = a|1\rangle + b|3\rangle + c|8\rangle + d|10\rangle$$ Where, of course, $|a|^2 + |b|^2 +... 0answers 706 views ### How does diameter of manometer affect the sensitivity of the manometer? I have a physics question on How the sensitivity of the manometer will change if a narrower tube is used for the manometer. Logically speaking, it seems normal for the sensitivity of the manometer ... 1answer 458 views ### Standard deviation as uncertainty of a single measurement If we have made the following several measurements of the quantity x that follow a normal distribution: 86, 85, 84, 89, 85, 89, 87, 85, 82, 85 The mean is 85.7 and the standard deviation(std) is ... 4answers 403 views ### How many significant figures should one give in stating an experimental uncertainty? [duplicate] How many significant figures should one give in stating a experimental uncertainty? For this purpose I found three rules: Experimental uncertainties should be always stated to 1 significant figure. ... 2answers 60 views ### How should a hydrometer be read? Probably due to surface tension the surface tends to curve near the hydrometer forming a meniscus. The question is whether it's correct to read the hydrometer at top of the meniscus or at the liquid ... 1answer 27 views ### Incorporate uncertainty of position to my result The data is a list of measurements of power$P_i$with estimated uncertainty$\Delta P_i$and another list with measurements of positions$x_i$and estimated uncertainties$\Delta x_i$. All the$\...
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Quantum theory is equally an epistemic (ie about information) and ontic theory (see "reality of the wavefunction" on Google Scholar). My question is about a theory that aligns with this, ie, the ...
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### Question when comparing two experimental results

In my textbook it says that if two experimental results vary less than 3$\sigma$ then they can be considered to have arrived at the same result. My question is how do you determine this "x$\sigma$". ...