Questions tagged [experimental-physics]
for questions about design, process, data, or analysis of experiments and observations.
2,491 questions
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New User - Help Please [on hold]
I had several physics questions (high level for me - rookie to you.) Initially I had written to a Nobel Physicist and asked for guidance on where I could ask some basic questions. His Administrative ...
2
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1answer
21 views
(What causes) the *other* Compton edge?
The question
If one exposes a scintillator to a gamma source, one will observe two features for each characteristic energy in the source: a photopeak, due to complete absorption of photons, and a ...
0
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1answer
24 views
Laser beam diameter with Interferometer [on hold]
Is it possible to measure laser beam diameter used as a source in an interferometer? If so, then how to go about designing such an interferometer?
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0answers
20 views
Arranging objects by mass [on hold]
I have n objects with different masses .
Say mass of n1=m1, n2=m2 .... so on.
I want to use concept of centrality in physics to arrange these objects in a field (computer simulation ) . Where object ...
0
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1answer
46 views
What are direct experimental evidences that quarks exist? [duplicate]
Now we have very established model of quarks explaining fundamental strong interaction. What are experimental proofs for existence of quarks and what is the name of physicist which made them?
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1answer
32 views
Significance calculation in particle physics?
I am wondering how does one calculate the significance of a "bump" in particle physics. Suppose I have a set of data:
for example,
in 100-200 GeV I have 700 events,
in 200-300 GeV I have 600 events,...
2
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1answer
25 views
What is wrong with my Cloud Chamber? I can't see supersaturated vapor or particles [duplicate]
I'm using black felt at the bottom, a small tin can, and black sponge around the inside of the can. I hot glued them onto the can, and then put 91% isopropyl alcohol in it. Afterwards, I used some ...
3
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0answers
37 views
+150
Near-room temperature DIY cloud chamber?
Conventional design of DIY cloud chamber uses IPA and cooling down to -26..-33°C (sometimes even lower, down to dry ice temperature).
What could be changed in design approach to shift operating ...
3
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0answers
34 views
Planck's constant calculated by photoelectric effect laboratory is off
I conducted an experiment today where I had to use a photocathode of unknown material (model: Daedalon Corporation Photoelectric Effect EP-05) and study the photoelectric (PE) effect to make a ...
0
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1answer
32 views
Transformer experiment
Are there any experiments conducted where we test a transformer by inputting more iron cores in to the original solenoid linking the output and the input voltage? I asked several questions on this but ...
1
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0answers
39 views
Dark Matter search, why DAMA collaboration does not publish $S_0$?
Results from recent experiments are starting to come in, mostly in the direction of not confirming the annual modulation measuremements published by the DAMA/Libra collaboration. In the search for ...
0
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0answers
7 views
What to say when making conclusions from experiment that tests a hypothesis?
I recall from inferential statistics, when performing a hypothesis test, that one either “fails to reject the hypothesis” or one “rejects the hypothesis” based on the outcome of the hypothesis test.
...
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1answer
33 views
Difference between expected $p_0$-value and observed $p_0$-value？
In the ATLAS paper for the higgs discovery, they used 2 kinds of different $p_0$-values. One is the expected $p_0$-value, the other one is observed $p_0$-value.
What's the difference between the ...
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0answers
22 views
Robert Boyle's discovery of electricity
I want to know what is the contribution of Robert Boyle in this discovery of electricity after Otto von gueriche?
1
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0answers
12 views
Compatibility of two bi-dimensional measures
As my last chance I try to post this question here, it seemed like a simple one but I have so much trouble finding an answer.
While doing the PET experiment, one needs to reconstruct the original ...
1
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2answers
67 views
+50
Experimental setup for 1 dimensional constrained frictionless motion
Physics textbooks are full of examples considering one dimensional constrained motion (in the gravitational field) with neglectible friction.
However I have never seen setups with curved paths where ...
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0answers
13 views
Uncertainty and percentage uncertainty formulas
So I am curious how does one derive the following relations for uncertainties:
Let $p=cxy$ or $p = c\dfrac{x}{y}$ and $r =z^n$ where $c=constant$
$\dfrac{\Delta p}{p} = \dfrac{\Delta x}{x}+\dfrac{\...
1
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0answers
28 views
Photo Multiplier Tube (PMT) and charge sensitive pre-amplifier
I have an H7195 assembly type Photo Multiplier Tube (PMT) used to be tested for single photon measurement. I would like to use the dynode output to check the spectrum by connecting to a charge ...
0
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1answer
60 views
How insulators and conductors were discovered?
I know Stephen gray has discovered insulator and conductor. But I want to know that how did he know which one is conductor and which one is insulator ? Please tell me the details how had he done that ...
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0answers
17 views
Doubt on application of uncertainty principle for an ion trap
Ion trap involves the application of an electromagnetic field to suspend and confine a charged particle.
At the centre of this picture, you see a saddle shape. This means that the ions are pushed ...
0
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1answer
18 views
Collimating a UV LED
I have a task of narrowing a UV LED (375 to 400nm) of diameter 5mm to 1mm on the surface of an object. The LED has a peak output power of 2.2mw (quite low). It has an half Intensity angle of 10 ...
0
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0answers
39 views
How to become an experimental physicist? [closed]
How to become an experimental physicist?
http://www.mostlyquantum.org/?p=536
Nobel laureate Dr. Gerard ’t Hooft has an online guide on how to become a theoretical physicist, but it is very hard to ...
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0answers
25 views
Stephan Gray's experiment [duplicate]
I have little bit of confusion about why cork as well as wood being an insulator act as conductor ?? http://lnr.li/YteKd (as given in the link in yellow colour).
And know for visual explaination see ...
1
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0answers
16 views
Why does the base-emitter voltage in NPN transistor become constant
The setup above shows the experiment that I have been working with. During the experiment, the current $i_c$ and the voltage $V_{be}$ were measured for increasing $V_{in}$. At some point, the current ...
1
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0answers
16 views
Mass Absorption coefficient with photon energy (Gamma ray)
We did an experiment for Gamma ray absorption and
we used Pb as the material (density of $11.35 g/cm^3$).
I am trying to find the corresponding photon energy for $\mu_m=0.087$ But I couldnt find it ...
0
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1answer
38 views
Effect of magnetic field on time period of a spring pendulum
Let us consider that we have a spring pendulum, and a magnet nearby. Assuming that the spring is being attracted toward the magnet, does the period decrease?
The formula of time period is = 2𝜋√m/k
...
1
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3answers
49 views
Why does the reconstructed mass of a particle have a fairly wide distribution?
In HEP experiments, a particle of interest (e.g. Higgs) is reconstructed using information about decay products, momentum, energy deposits, angle of those particles, etc. The invariant mass of the ...
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0answers
28 views
What is the equation of time period for a bent wire pendulum?
Just like there is a formula for time periods of a simple pendulum and a spring pendulum. Is there a formula for the time period of bent wire pendulum? There does not seem to be much research done on ...
0
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1answer
17 views
Does the hypothesis in an experiement need to mention the independent and dependent variables?
My current understanding of a hypothesis is just that it is 'an educated guess to explain a phenomenon'. Which follows that in an experiment, any guessing statement can be correct as long as it can be ...
4
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1answer
77 views
Detecting the electroweak unification in data of quark gluon plasma
Electroweak unification is discussed in the Big Bang model and variant proposals, and there is a transition at energies of 100 GeV where the EW symmetry is unbroken and a quark gluon plasma phase ...
39
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2answers
11k views
Why doesn't increasing the temperature of something like wood or paper set them on fire?
Imagine we have paper book. If we put this into a pan and increase its temperature, this book would not catch on fire. If on the other hand the book interacts with this heat source directly, it does ...
8
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0answers
173 views
Building the Penrose Unilluminable Room [closed]
As an architect with an interest in the natural sciences I was intrigued when I first learned of the illumination problem and its proposed solutions, specifically the one proposed by Roger Penrose in ...
0
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0answers
19 views
Experiments measuring temperature dependence of graphene's specific heat in low-temperature regime?
I am currently studying the Debye model and I've found out that for two-dimensional materials the specific heat in low temperature limit should scale with temperature as ~T$^2$ as opposed to the "...
1
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1answer
35 views
What accelerator energies and types would be needed to explore electroweak unification, and if accessible, what would be the likely observables?
Question originally referred to electrostrong, but I actually meant to ask about electroweak. Edited to fix, but this is why there's an answer referencing ES not EW - that's my bad.
Broadly as the ...
1
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1answer
28 views
Normalize accelerometer data based on non-central location
I am trying to "normalize" accelerometer data for a sensor that is not centered on a car. In the image below, you can see how centripetal force changes based on location.
In my case, I only have one ...
0
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0answers
23 views
Calculating uncertainty from $\ln$ equation [duplicate]
I am using an equation $\theta=\theta_0 e^{-\beta t}$, which rearranges into the equation
$\ln(\theta) = \ln(\theta_0) - \beta t$ in order to plot a linear graph.
I know the error for both $\theta$ ...
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0answers
31 views
Misconceptions in Stephen Gray's experiment on conduction [duplicate]
In his experiment I find a lot of misconception like cork acting as a conductor plz explain whether this experiment is correct or wrong
0
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1answer
30 views
Poisson statistics & ratios
The rule of thumb I know for the error on a count for random sampling is that it goes as the square root of the count. For instance, if I observe a radioactive source for $1$ minute and measure $100$ ...
0
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0answers
32 views
Foucault's pendulum; ball bearing?
Is is a ball bearing necessary to prevent the cord from twisting in a Foucault pendulum?
1
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2answers
48 views
What should be the independent variable in a resistance experiment?
I was asked a question by a student today and I have been pondering about it for a while now. In an experiment to measure resistance of a conductor, should we vary voltage across the conductor and ...
2
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0answers
13 views
What distinguishes a duoplasmatron from simpler methods of ionizing gases?
I've been looking at duoplasmatron designs and am not sure what makes the basic function of a duoplasmatron different from simply ionizing H2 gas by sending an arc discharge/electric current through ...
2
votes
1answer
74 views
Determining the focal length of a convex lens (no-parallax method)
This is about the experiment where we determine the focal length of a convex lens using the graphical method,(the no parallax method).
In the situation where the image moves opposite to the direction ...
1
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0answers
13 views
Geometry of the electrodes in experiments on the photoelectric effect
My school uses a commercial apparatus for freshman student labs on the photoelectric effect, but the documentation, written for students, is at a very basic level and seems to oversimplify or not ...
-1
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2answers
50 views
Measuring the Thickness of a Paper
I'm supposed to come up with a way to measure the thickness of paper. I've come up with the following approach.
Let us suppose we have a paper of thickness $?$, length $a$, breadth $b$, density $\rho$...
2
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0answers
44 views
Why does the iron and gallium alloy called Galfenol generate electricity under impact forces?
The scientists in the experiment took a rod made of galfenol - which is iron doped with gallium - placed it under high pressure impact forces on both ends while under a magnetic field and discovered ...
0
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0answers
32 views
Bayesian approach for setting upper limit
In the presentation by Cowan, on slide 18, he explains the baseyian approach of setting upper limit in parameter estimation.
What I didn't get is the formula written. Bayes's theorem is like $P(a|b) \...
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0answers
77 views
Why cork act as a conductor in Stephen Gray's experiment? [closed]
Why in Stephen Gray's experiment,
cork as well as wood ,which is an insulator, acts as conductor?http://lnr.li/YteKd (as given in the link in yellow colour).
And now for visual explaination see the ...
0
votes
1answer
26 views
Will a 100MeV muon and a 50MeV muon deposit a different amount of energy in a scintillator?
I have a question where I need to calculate how much energy a $100\,\mathrm{MeV}$ muon will deposit in $1\,\mathrm{cm}$ of scintillator. I know that the muons lose energy about $2\,\mathrm{MeV/(g/cm^2)...
0
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1answer
82 views
Reactionless propulsion theory. Will resistance to the flow of electricity within a moving conductor result in a propelling force?
I believe that a conductor which is physically moving in the opposite direction to the flow of electricity will result in the motion of the conductor being resisted and this resistance will cause the ...
3
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1answer
65 views
What Does Up-Down Asymmetry Mean?
There is strong experimental evidence (reported on in the linked paper), from more than one high energy physics experiment, that up-down asymmetry is present in the decays of certain charmed baryons. ...
