Questions tagged [experimental-physics]
for questions about design, process, data, or analysis of experiments and observations.
2,938
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How are molecules put into superposition in lab experiments?
What process needs to be done on molecules to put them in a state of superposition in laboratory experiments?
I understand that it involves working with systems cooled down to very low temperatures. ...
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How do single-pixel cameras work?
To obtain images using a single-pixel camera we need a Digital Micromirror Device (DMD) because single-pixel cameras only possess a single detector (article).
From my understanding, a single-pixel ...
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What is the difference between Keithely model 2612 and 2612A
I'm looking to buy an additional Keithely for my setup. I've been looking at the Keithely 2612 and 2612A, but I was wondering what the difference between the two is. I've been looking in the datasheet,...
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1answer
30 views
What goes wrong in solving for an uncertainty (when expressed in quadrature)? Is there anything wrong?
Supposed I have the following expression for the error in an arbitrary variable S:
$\frac{\delta S}{S}=\sqrt{(\frac{\delta q}{q})^2+(\frac{\delta w}{w})^2}$. What is wrong with concluding that $\frac{\...
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2answers
149 views
Is it possible to know that an object is at a certain location without observing any of its interactions?
Let's say there is a cube in deep space. There is no light or force being applied to the cube. Is it possible to know if the cube exists in this scenario?
Sorry if the question seems too simplistic. I ...
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1answer
24 views
Fibre optic -physics
What is different between the lost of coupling and efficiency overall coupling ?
I know both of them (power out/power in)e.g (5%) that means is 5% light transmission and 95% lost.
2
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1answer
26 views
Best way to measure rebound height of a ball accurately and precisely?
We were tasked with designing an experiment based on measuring the efficiency of a bouncing ball. And so for this we would have to calculate the rebound height experimentally to obtain a quantity ...
3
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1answer
56 views
What is the difference between Uncertainty and Standard Deviation?
In physics lab class we are learning about uncertainty and propagation of error. Last week we learned about how to find uncertainty of a calculated value using the equation $$\delta_f = \left(\frac{\...
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1answer
20 views
Direct and in-direct measurments
I have seen and heard this many times that a certain (physical) measurement is "direct" or "indirect". What is the characteristic or definition that sharply separates these two ...
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40 views
Is it possible that the frequency of a microwave oven changes because of an error?
Somebody complained on a forum, that his microwave oven heats up the plate instead of the food. One explanation that the material of the plate is not suited to microwave ovens. Another explanation ...
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5answers
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General relativity (and other theories) when proven wrong
So, I have been watching some science videos regarding Einstein's theory on general relativity and until today the predictions based on his equations have been proven to stand.
My question would be, ...
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2answers
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Computing a quality factor of multiple measurements [closed]
Suppose I measure the same quantity twice with two methods, first I get 0 with 0.001 uncertainty, then I get 1 with 0.000001 uncertainty. We can see from this most likely there is something wrong with ...
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First superconductors’ failure to follow BCS theory
Which superconductors were the first to fail to follow BCS theory?
And in what year was it?
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151 views
Is there tested proof of time dilation in the stationary frame, from the perspective of the moving frame?
I know that they have proven time dilation in the moving frame from the perspective of the stationary frame, eg comparing two cesium clocks in the jumbo jet test.
But have tests been done on the other ...
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2answers
117 views
Why is a magnetic field of a permanent magnet not considered energy?
The first law says you can’t create energy. OK, but you can give energy to a ferromagnet and magnetize it. Then you can magnetize as many other ferromagnetic materials as you want, and not diminish ...
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1answer
30 views
Understanding how Stern–Gerlach apparatuses work
I'm studying about the Stern–Gerlach experiment. I'm having some hard time to figure out how the Stern–Gerlach apparatuses work. I have the following question:
Transfer a beam of electrons through ...
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0answers
20 views
Absolute error/Least count of Theodolite
I have to calculate the absolute error of a theodolite. My theodolite has:
smallest division on main scale = 1 degree ;
smallest division on vernier scale = 2 minutes of arc ; number of divisions of ...
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0answers
11 views
Infrared-safe and collinear-safe jet algorithms
A good algorithm for reconstructing jets in an experiment requires "infrared safety" and "collinear safety". This means that the configuration of the reconstructed jet must not ...
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34 views
Why do Xe-135 and Zr-88 have a surprisingly large thermal neutron capture cross-section?
Why do Xe-135 and Zr-88 have surprisingly large thermal neutron capture cross-sections?
The probability that a nucleus will absorb a neutron—the neutron capture cross-section—is important to many ...
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Which has the higher absolute uncertainty and why? An electric vernier caliper or a micrometer?
I was answering some questions in a textbook and it asked: Which one has the highest absolute uncertainty? A ruler, a voltmeter or vernier caliper?
I went with the ruler because the absolute ...
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31 views
Can a glass cup be used to collect positively-charged air ions from the Earth's atmosphere?
I am wondering if the positively-charged air ions that are descending down from Earth's Ionosphere can be collected using a glass cup. Since a glass cup will allow an electric field to pass through it,...
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21 views
Data for experiments of Doppler effect
I am a high school student that has attempted to carry out the experiment for the Doppler effect using an RC car going at constant speed, a sound source at constant frequency and phyphox app to ...
6
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2answers
197 views
Is Thibado’s Graphene Brownian Capacitor Charger Perpetual Motion of the Second Kind?
In Fluctuation-induced current from freestanding graphene (peer-reviewed version on Phys. Rev. E, note: behind a paywall) Thiabado, et al, report the extraction of work from brownian motion. The ...
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18 views
Physics static and systematic errors, total errors?
For a measurement result $X\pm x_{\text{stat}}\pm x_{\text{syst}}$ is the total error:
$$\Delta x_{tot}=\sqrt{x_{\text{syst}}^2+ x_{\text{stat}}^2}$$
But why is it squared, calculated and then the ...
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0answers
11 views
Sensitivity vs efficiency
What is the difference between the sensitivity and the efficiency of a detector. In the detector books I found they seem to be treated as 2 different concepts, but based on the descriptions, I can't ...
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13 views
References for effective viscosity experiments
Presentation
I am studying the following fluid mecanics problem :
let's consider a domain $\Omega$ filled with water. In this fluid, we can find perfectly spherical particles of radius $\epsilon h$ ...
3
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1answer
37 views
Distinguishing between quark and gluon jets
How do experimentalists at the LHC differentiate between jets produced by quarks and those produced by gluons. I know that for b quarks there is a b-tagging method, but what do they do for the others ...
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2answers
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How can an object (meteroid, vehicle) bounce off the atmosphere?
Recently, a meteroid bounced off the Earth's atmosphere. IIRC vehicles such as the returning Apollo craft also had the risk of bouncing unless they came in at a precise angle.
How is this possible?
...
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1answer
13 views
How can the metal sphere connected to a ground in a Van de Graaff generator becomes electrically charged?
I am currently experimenting with a homemade Van de Graaff generator. The design looks just like in the Wikipedia page here. In many designs of the VDG, I see that the bottom comb is connected to a ...
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2answers
46 views
Troubleshooting a homemade Van de Graaff generator [closed]
I am building a homemade VDG generator and it does not seem to provide any electrical charges. My construction is as follows:
The top roller is PVC, it is "pierced" (I don't know the ...
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0answers
35 views
Does the gravitation force depend on temperature?
C. Y. Lo says:
"According to Newton and Einstein, gravitation is independent of the temperature, but experiments show that the gravitation of a metal is reduced as temperature increases. ~~~. &...
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How does shot noise non-correlation of a split beam appear in an XY oscilloscope plot?
I'm currently reaching Bachor's Guide to Experiments in Quantum optics and trying to wrap my head around an experimental result.
Suppose a laser beam passes through a beam splitter, and the 2 ...
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2answers
30 views
Measuring resistance of a resistor - what to do with multiple readings
So I want to measure the resistance of an unknown resistor.
My setup is shown with the circuit diagram and I use the variable resistor to collect a range of readings of current $I$ through and ...
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1answer
29 views
Calculating rebound force of an object
There is already a question similar to this.
I am wondering if there is any way to calculate the rebound force if the impact time is unknown. Here are the knowns:
mass of object
height of drop
height ...
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2answers
38 views
Number of significant figures on exponentiation
From Braddick's The Physics of Experimental Method (1963):"It should be remembered that the number of significant figures in a number $y$, and one derived from it, say $e^y$, are not always the ...
2
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1answer
58 views
What evidence is there for the gravitational acceleration of a free electron?
According to Newtonian gravity (in the absence of other forces or obstacles) a free electron (not moving at high velocity) should (because it has mass) fall towards the Earth's centre with the same ...
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35 views
Lifting a heavy object with multiple people
If an average person can lift say 100 lbs alone, how many pounds can he lift with a friend (the same size)? I've heard each person can lift 3 times his usual amount when with another. Is that ...
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1answer
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“A resonant state unbound to neutron decay by at least 100 keV was identified” Could you guys please explain this clearly?
Does it mean that If we provide 100 KeV energy to the nucleus in that resonant state then it will decay through a neutron emission?
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1answer
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Accuracy of Newton's law of cooling
I've made an experiment to verify Newtn's law of cooling, but while doing the analysis, my results don't fit accurately with the data collected (303 data using a sensor). According with my initial ...
2
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1answer
68 views
Collimation issue with an DIY echelle spectrograph
I am trying to make an educational echelle spectrograph using easily available materials, basically in a cardboard box. An echelle grating (36 lines/mm) needs another prism to do a cross dispersion ...
0
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1answer
22 views
What does QL mean in experimental condensed matter physics (thin film growth)?
In literatures of thin film growth I often see the unit QL. It often occurs at contexts like "a 64 QL film," "the growth occurs QL-by-QL," and "the growth rate was found to be ...
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2answers
44 views
Does it make sense to average data taken continuously as the system evolved?
I have a simulation where a bunch of particles are moving. Every time step I fit a gaussian (through non-linear least squares) to the distribution of speeds. Here I end up with a temperature $T_i$ and ...
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1answer
21 views
Superposition of Microwaves experiment? How does it work?
Please can someone help me out with this experiment and see if this is correct?
So the experiment consists of one metal sheet that fully reflects microwaves (and is fixed in its position), and the ...
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16 views
Experimental evidence of Pauli principle for non-bound fermions
I mean electrons in atoms/molecules/solid bodies not count here.
I heared of an experiment measuring the degeneracy pressure of a fermion gas.
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39 views
Can a detector fail to detect a wave of electromagnetic radiation because the wave's amplitude is at or near its minimum?
If a very brief wave (perhaps a single photon, or maybe a soliton?) is at its minimum (a 'node') when it encounters a detector, would it still be detected?
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How do you get the total energy of an event for a detector array?
THE SET-UP: The air-shower detector array made out of six detectors. The detectors are composed of a scintillator and a SiPM (Sillicon Photomultiplier) each. Depending on the shower size, one or more ...
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What does $LS$ coupling and $jj$ coupling signify?
When we consider $1s2p$ electrons in $LS$ coupling we get one singlet and one triplet but in $jj$ coupling, we get $2$ doublets.
I know the mathematical (quantum number) work behind it.
But what I don'...
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What does to smear energy means in particle physics?
I'm reading about event selection for a particle physics experiment, english is not my first language, and there is this phrase I can not translate and understand: "The energy of the showers is ...
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142 views
Experimental Implications of Wigner Distribution
I'm interested in the experimental implications of the Wigner quasiprobability distribution in quantum physics, but haven't been able to find anything that addresses my particular question.
...
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Why doesn't Franck-Hertz experiment ionize the gas?
In the Franck-Hertz experiment, electrons are accelerated through a gas and their kinetic energies are measured. This produces peaks and troughs which are indicative of changing energy states in the ...
