# Tag Info

## Hot answers tagged experimental-physics

7

In a cloud chamber (or any other detector) the particles are moving through a material medium, so they steadily lose energy (that can also suddenly lose energy which results in a kink in the track). Less energy means lower speed which means less momentum $p$, and the radius of curvature $R$ goes by $$R = \frac{p}{qB} \;,$$ where $q$ is the particles ...

3

This is because of a principle known as lepton number conservation. "Leptons" are a class of elementary particles which includes both electrons and neutrinos (the only stable examples), as well as their associated anti-particles. The lepton number is the total count of leptons in a physical system, where that anti-leptons are counted as though they were a "...

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Low energy electrons lose energy to ionization of the medium they’re traversing. The ionization comes from the charged particle interacting electrically with atomic electrons as it moves through atoms. This is a good thing: that ionization is what the chamber is detecting and displaying.

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As can be seen in the label of the picture you show, it is a bubble chamber picture. The label says : " A bubble chamber works on the same principle as a cloud chamber except that spiral tracks are seen as well." Cloud and bubble chambers make charge particle tracks visible by their scattering off atoms of the medium, ionizing them and creating the ...

2

Here are some things for you to think about. First, to reduce the resonant frequency of a metal tuning fork requires the removal of enough metal from the crotch of the fork so as to significantly increase the effective length of the tines. It is highly doubtful that you did that with just a couple of passes of a metal file. Second, to get a reliable ...

2

This is basically a string instrument which makes the holes similar to an instrument's sound holes. The effect is to make the audio from the strings louder. If the box were sealed, the vibrations set up by the string could be dampened by the pressure from the air inside. The box can vibrate farther when the air is free to move in and out.

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For those of us who spent many hours slaving over an ion accelerator to crank out Rutherford Backscattering Spectrometry spectra to measure composition profiles in thin films, the accuracy of backscattering theory seems to have been pretty well established over the last 50+ years. But, that paper seems like a nice physics laboratory write up. But, your ...

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The plus-or-minus figure that you list ($\pm0.0021\,\mathrm{GeV}$) is the error on the mean and not the width of the distribution which is very wide. The usual source for looking up such basic particle data is the Review of Particle Physics published and maintained by the Particle Data Group. The Review is availble for download and on-line browsing on the ...

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Historically the first field of theoretical physics based on the concept that heat is motion of molecules is kinetic theory of gases The predecessor of the kinetic theory was caloric theory According to the wikipedia article in 1857 Rudolf Clausius developed a theory that included rotational and vibrational modes of molecules as repositories of energy. As ...

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So you have measurements of the time it takes to fall, not the acceleration of a falling mass. (Hence the units: counts per second vs seconds). If there are $N_i$ counts in a bin, your estimate of the uncertainly is $\sqrt{N_i}$. If you scale that by a parameter $\alpha$ to get a histogram value: $$y_i = \alpha N_i$$ and  \Delta y_i = \alpha \sqrt{N_i}...

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the measurement tool is called an electrostatic voltmeter. I do not know if any exist that you could slip into and out of your pocket to make field measurements though.

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The microcosm of elementary particles, atoms, molecules is described mathematically by quantum mechanical models, very successfully. Quantum mechanics give only the probability of something happening. In classical physics models, if something is possible one can control the parameters so it can happen. The system is deterministic. In quantum mechanics if ...

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Yes, but why bother? There is an incentive to make antiparticles, for example beams of antielectrons or antiprotons, see for example https://en.wikipedia.org/wiki/Antiproton_Collector Atoms of anti-hydrogen have also been produced: https://www.nature.com/articles/nature21040.pdf

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This must be a more common experiment than I would have imagined. My own students are doing a similar experiment right now though the analysis differs a bit. It might be best to talk to your TA or professor to gain an understanding of how they expect you to propagate the uncertainty. For my own students, I would ask them to have their chosen fitting ...

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Your choice of an example considering resistance complicates matters which I will mention later. If the error is the maximum error then using the first equation you are finding an error based on the assumption that both values have a maximum error simultaneously which is not a very likely event. This means that the error found this way is an over ...

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I have what I think is the correct answer to the second question, where I think there is are some surprisingly interesting physics. If you place an optical flat on top of another flat optic, the optical flat will indeed sit with a layer of air between it and the underlying optic. Over time, the air escapes, and gravity will optically contact the two optics. ...

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The extraction process of the carrier isotope after each run was imperfect. Only about 95% of the isotope were extracted and the other 5% remained inside. Alternating between two different carrier gases allowed to distinguished between the isotope used in the current run and the remains of the other isotope still present from the previous run. See the ...

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