# Tagged Questions

for questions about design, process, data, or analysis of experiments and observations.

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### Extreme charge density in thin capacitor plates

Suppose we made a 1 square meter parallel plate capacitor from two sheets of graphene separated by a very strong dielectric of arbitrary thickness. Then we charge the capacitor just short of the ...
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### Experimental proof of gravity propagation? [duplicate]

The last research aim to find gravitons which are boson, so if I correctly understand they are virtual particles. Out of theorical assumptions, Is there exist an experimental proof that the ...
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### Does gravity affects on electrons in a noticeable way? [closed]

Is there a way to force a free electron move in a low speed in order to observe it actually hitting 'on the floor'?
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### How to compare optical fibers of different material, NA and diameter

For an experiment I would like to figure out how different optical fibers behave in terms of losses at both ends and their attenuation for a given wavelength. Let's say, I have three different ...
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### Do liquids creep from cold to hot like gases?

Consider the U-tube water experiment below with the left red block at 10C and the right red block at 90C. I think the right level will become about 3% higher than the left level simply because hotter ...
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### How to measure 8 μm surface bumps?

I want to measure surface bumps which are larger in size than $8\ \mathrm{\mu m}$ on a uncoated plastic mirror. So it can be any number of smaller bumps and that would not effect the application. I ...
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### smallest possible length of copper wire, where I can measure capacitance via multimeter [closed]

I am a new highschool physics instructor and I want to show to my students the basic concept inside the capacitors. i plan on showing them via simple 2 copper wires side by side each other, supplied ...
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### Rate in Fermi's golden rule

There is a very clear derivation of Fermi's golden rule (actually Dirac's) here. Everything runs smoothly until, somehow, the equivalence $$\Gamma_{a \rightarrow b} = \frac{P_{a \rightarrow b}}{t}$$...
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### Is there any evidence of black holes existing? [duplicate]

Yes, I am aware of observations of "massive objects", for example near the center of the galaxy. But is there any evidence that the object in question is a black hole, with all its commonly attributed ...
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### What are some experiments verifying Maxwell's 4th equation?

Please give me the link to some paper, website or book that you know about which discusses in detail some experiments which quantitatively verify Maxwell's 4th equation, which is \quad \nabla\times{...
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### Measuring the Dirac field

If the Dirac field $\psi(x)$ is to the electron as the Electromagnetic field is to the photon, why is it that we can measure the Electromagnetic field, whereas the Dirac field we cannot?
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### Machine readable database of gamma lines

Friends of mine did a lab experiment where they recorded $\gamma$-spectra in the range from 0 to 1500 keV with a soil sample. The data contains some background and a couple sharp peaks at different ...
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### Measuring expectation value in quantum field theory and in quantum mechanics

There is a way of calculating the vacuum expectation value $\langle 0|\hat\phi|0\rangle$ theoretically in a quantum field theory like there is a rule to compute expectation value of any operator A (...
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### Beta decay - Relative probability of electronic conversion for different disexcitations energies

I'm studying, experimentally, beta decay phenomena. Internal conversion of electrons happens when we have a sobreposition between a excited nucleus with it's electronic cloud. The colision between the ...
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### The maximum distance for which Coulomb's law has been verified?

We know that Coulomb's law, $F_{12} = \frac{kq_1q_2}{r^2}$, was experimentally verified for small distances by Coulomb himself at the and of the XVIII century. The question is what is the maximum ...
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### How to measure $\mathbb{L}^2$ and $L_z$ simultaneously

What does an experiment look like, in which both quantities are measured simultanously?
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### Measure ball's acceleration down inclined plane

If I am asked to devise an experiment to find an expression for the acceleration of a uniform sphere (ball bearing) rolling down an inclined plane, as a function of the angle of incline. Hence deduce ...
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### How does one build a framework of sensors from nothing? [closed]

I would like to understand how you can go from nothing to a framework of sensors you can use to try out things in physics/thermodynamics. That is, everything has to be bottoms up, nothing premade ...
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### Simple Stern-Gerlach Apparatus Orientation

I have been reading Townsend(2012)A Modern Approach to Quantum Mechanics. In the first chapter, he introduces the idea of intrinsic spin angular momentum, and some of its strange quantum properties ...
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### How do you calculate theoretical ratios of angular velocity final and angular velocity initial? [closed]

I'm asked to calculate the "Theoretical Ratio". ($\omega_f/\omega_i$) I have Inertia of the Disk = $I_{DISK} = .0094115713$, I have Hoop Inner Radius = $I_R = 55.725$ So I am supposed to use the ...
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### Search for unpublished note on Magnetic Monopole Detection

Design of an electromagnetic detector for Dirac monopoles by Luis Alvarez This is an unpublished 1963 note from Lawrence Radiation Laboratory (Physics Note 470), and is heavily cited in all papers on ...
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### Wu experiment beta decay

maybe it's a stupid question. But in Wu experiment she showed that parity in not conserved in beta decay. So how to say on general that this is true for any weak force interaction?
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### Fiber holder with 'vacuum' holes.

I'm a student in my third semester and am currently working with workgroup in our physics department. Last week our lab got access to liquid nitrogen and we are fiddling around with fibers in ...
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### Help me understand Pound and Rebka's experiment

I am a second year undergrad physics student and up until now have done some classical mechanics and some electrodynamics. For some reason I have always been really interested in light. A couple of ...
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### How deep within the sample can the DOS(density of states) be detected by STM(scanning tunnel microscope)?

Using STM equipment, we can get the LDOS(local density of states) on the surface of a sample. I want to know whether the LDOS within the sample(not surface) can be detected by STM. what is the ...
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### How do we know which direction heat flows? From cold to hot, or from hot to cold?

I'm trying to figure out which direction the heat flows. After many google searches I've determined it flows from hot (higher energy) to cold (lower energy). My question tho is, how do we ...
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### Detection of the He-nuclei in the historical Rutherford scattering experiment

Which method did Rutherford use to detect the Helium nuclei in his scattering experiment?
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### What are the original papers on the hydrogen spectral lines?

I am trying to find original sources for experiments that had observed spectral lines from hydrogen or other gases. I am looking into experiments that motivated Niels Bohr to write his ideas on the ...
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### Double slit experiment mechanism

Can someone explain the mechanism that sets in motion the electrons in the experiment? Is it an electro-magnetic force? If so, I think it's not right to describe the motion of the electron as a '...
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### How did experiments affect the development of quantum mechanics? [closed]

What were some of the major experiments that helped to develop Quantum Mechanics? I've read about the Stern-Gerlach experiment and double-slit experiment. But what role did experiments play? Did they ...
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### Sterile neutrino constraints (summary of results)

Constraints on sterile neutrinos come from an amazingly wide range of different sources. From astrophysical observations (review1, review2) to particle physics experiments (MiniBooNE, Daya Bay, LSND, ...
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### Elementary graphical error analysis

Suppose you analyze experimantal data with pencil and piece of paper, one simple method is to plot the data in a linearized way with error bars. Suppose you are interested in the slope of this linear ...
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### Is it possible to make a “wire-free” Bungee jump?

Wireless bungee jump I think it could be possible with magnets, and the suit of the person has to have a different magnetic camp form the floor camp. But I don't know if the person can rebound. Is ...
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### A confusion with solenoidal windings

I have seen in solenoids, toroids, transformers, electromagnets and machines that the core is pretty insulated. Over this the winding coil is wrapped but it is a bare coil (turns are not insulated to ...
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### Have we observed sufficient extra-solar planetary systems to establish a planetary distribution pattern? [duplicate]

From Kepler And Extra-Solar Planetary Observations As of January 2015, Kepler and its follow-up observations had found 1,013 confirmed exoplanets in about 440 stellar systems, along with a further ...
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### Gamma spectroscopy - Fitted Singlet

I'm using some gamma acquisition and analysis software. When I ask the software to do some sort of Nuclide Identification, almost every single peak in the generated output is marked with "F". ...
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### I have some questions about reproducing Young's double slit experiment

I want to reproduce Young's double slit experiment for a school project. For the slits I am thinking making cuts in aluminium foil or maybe do something with pencil leads like this instructable ...
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### What would be the limitations of this lab?

I was wondering what the limitations of this experiment would be. I found the static coefficient of friction between wood and sandpapaer by using a Newton spring scale and I believe that some of the ...
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### What is the smallest item for which gravity has been recorded or observed?

What is the smallest item for which gravity has been recorded or observed? By this, I mean the smallest object whose gravitational effect upon another object has been detected. (Many thanks to Daniel ...
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### How do space probes identify molecules?

How does a space probe identify molecules without actually obtaining the molecules? The common identification techniques I can think of are spectroscopy and magnetic resonance, but for both of them, ...
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### Michelson–Morley experiment's aether; Why is the time gained from travelling downwind less than that lost travelling upwind?

From the Wikipedia article on the Michelson–Morley experiment, explaining one of the concepts behind the landmark experiment: "If the Earth is traveling through an aether medium, a beam reflecting ...
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### Raw data acquirable from amateur astrophotography

What raw data can I possibly acquire from an 8" Classical Dobsonian Telescope, and a DSLR? Could anything eye-opening to amateur astronomers be computed or calculated first-hand with such equipment? I'...
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### Use of normal distribution in measurement error theory

When you study an experimental results you assume that normal distribution describe random error, specially in lab courses in K12. Is this true for every random component error treatment in physics? ...
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### How do I measure speed accurately without any turning wheels?

Consider a pod (about 50 ft long and 15 square feet wide) that levitates using air pressure that shoots through the bottom and travels through a tube that's at low air pressure (about 100 Pa). It ...
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### Graphing $E_p = E_k + E_{rot}$

I am measuring the moment of inertia of a flywheel and using conservation of energy to work out the value (I am ignoring friction). So for the experiment I have to roll the flywheel down a slope (I ...
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### Magnetic flux density of a solenoidal electromagnet

I am designing an electromagnet which will be used to test magnetic sensors. So I used to formula found at hyperphysics which relates the magnetic field flux density to the number of turns, the ...
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### Residuals are normally distributed

I did not know whether to post this question in the Physics or Statistics section of StackExchange, but the question involves the application of statistics to the analysis of experimental results. I ...
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### Can someone clarify whether the recent experiment closing all remaining loopholes to Bell's Theorem really shut the door on local realism for good?

I saw this recent article on Phys.org that purports to close all remaining loopholes that previous experiments on violations of Bell's inequality left open. My question is, does this really close the ...