Questions tagged [experimental-physics]
for questions about design, process, data, or analysis of experiments and observations.
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How did Henry Cavendish deduce the inverse square law in electrostatics from his experiment in 1772?
An elegant experiment in 1772 by Henry Cavendish. Cavendish charged a spherical conducting shell that contained within it, and temporarily connected to it, a smaller sphere. The outer shell was then ...
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6 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
23 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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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?
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11 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 ...
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10 views
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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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{\...
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0answers
21 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 ...
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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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16 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 ...
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1answer
17 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 ...
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38 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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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 ...
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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 ...
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On the Time Reversal Noninvariance in Quantum Physics [closed]
Why the experimenters for many years already do not want to recognize the quite obvious experimental fact of inequality of forward and reversed processes in quantum physics?
Why are the theorists ...
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0answers
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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 ...
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1answer
34 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
...
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3answers
48 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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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 ...
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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 ...
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1answer
75 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 ...
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2answers
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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 ...
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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 ...
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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 "...
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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 ...
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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 ...
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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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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
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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 $100$ ...
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0answers
31 views
Foucault's pendulum; ball bearing?
Is is a ball bearing necessary to prevent the cord from twisting in a Foucault pendulum?
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2answers
47 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 ...
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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 ...
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1answer
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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 ...
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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 ...
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2answers
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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 $\rho$...
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0answers
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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 ...
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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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76 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
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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)...
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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 ...
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1answer
64 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. ...
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1answer
30 views
Water equilibrium while dying of thirst in a confined space
I'm trying to understand what happens with the water while a person is dying from thirst in a deep, narrow mine shaft. Assuming he has dry food for a long time, and some liters of water. Dry air is ...
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0answers
17 views
Crookes radiometer showing radiation pressure
Originally, the Crookes radiometer was meant to measure the light intensity. For decades the explanation for its rotation was debated. It is now known that the rotation does not originate from ...
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1answer
42 views
Earth rotation with atmosphere
Note: This might be a very dumb question
Considering Earth's rotation on its axis, I was thinking it made sense for the outer sides of the Earth to have a significantly higher tangential speed, ...
2
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1answer
29 views
Unknown pulses from SiPM without any source or detector?
I have a SiPM set up with its PCB, no amplification at all, reading out to an oscilloscope. If I supply 29.8 V, which is the maximum power (with overvoltage), I get some random peaks on the ...
3
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1answer
59 views
Why Aren't Hadron Masses More Useful In Determining Standard Model Constant Values?
Some of the most exquisitely precise experimental measurements in all of physics are the masses of the various hadrons.
Consider these examples: the proton mass is known to eleven significant digits. ...
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CP violation measurement
I have a question regarding the measurement of CP Violation in experiment. How is parity measured in an experiment? I know that in the direct measurement of CP violation we look at a particle process ...
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2answers
115 views
Why is the resolution or measurement uncertainty of $G$ so bad?
I sorta know how the Cavendish apparatus works, and I know that "Gravity is an extremely weak force" for subatomic particles in comparison with the E&M or nuclear forces that act on these ...
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What is the practical Length of photons, in vacuum for example [duplicate]
From practical point of view we know the width of photons is proportional to wavelengths (experiments for light going through tiny holes: it starts with a specific size of the holes, etc). And nobody ...
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7 views
Neutron life cycle in fast reactor
How does the four factor formula change in the case of fast reactors? Where can I get a detailed discussion of neutron life cycles in fast reactors?
