Questions tagged [experimental-physics]

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

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2answers
90 views

running on the outside of a moving train

Seen a few films lately where the hero runs on top of a moving train, for example "Under Siege 2". It gives the impression that the train is moving quite fast (presumably its normal operating speed on ...
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1answer
192 views

Light Bulb Resistance

If the voltage and current of a circuit containing a light bulb are measured using a multimeter after consecutively lowering the voltage (building of a data set), what (type of) function will describe ...
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66 views

Coulomb Barrier - Nuclear Physics

When we calculate the Coulomb's barrier we usually assume that two nucleus (target and projectile) just touch each other so the barrier: $$E_{cb}=\frac{0.96Z_1 Z_2}{A_1 ^{1/3}+A_2^{1/3}}\text{ MeV} \...
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3answers
107 views

Why transcendental terms in the laws of nature are dimensionless?

Through my years in nuclear engineering, it has always been the case that in physical relations, the arguments of transcendental functions, e.g., the exponential in the law of radioactive decay, $N=...
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13 views

Non-neutral plasma axial vs radial timescales in Penning-Malmberg trap

I have been reading about trapped electron plasmas, and computer simulations for plasmas in Penning-Malmberg trap. Can somebody help me to understand why the timescale for radial transport is much ...
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1answer
68 views

Why does this sine wave like pattern appear in cut plastic?

I was opening a package that was plastic wrapped from the super market with the prong of a fork, and this pattern (in the picture) emerged: I started by poking the prong of the fork (right side of ...
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0answers
52 views

A Physics Book for Experimental Evidence

I have come to notice how Physics is developed: we do some experiments and (from them) draw concise conclusions, which we call physical laws. Then we come up with the appropriate mathematics to—fully ...
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1answer
97 views

In neutrino oscillation experiment, what are the Feynman diagrams involved for the *detection of the neutrino* in the detector?

In neutrino oscillation experiment, for example NOvA [but it could be other if you prefer], what are the diagrams involved for the detection of the neutrino in the detector ? I have explored inside ...
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2answers
116 views

Will state of water change in certain condition? [closed]

Imagine I have an iron tank with a $20~\mathrm{pm}$ hole on it. Then I completely fill it with water and use a pump to get the water out of that hole. What will come out, water or gas?
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Why is a leading digit not counted as a significant figure if it is a 1?

Reading the book Schaum's Outline of Engineering Mechanics: Statics I came across something that makes no sense to me considering the subject of significant figures: I have searched and saw that ...
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1answer
71 views

Where can I find the original experiment that lead to this discovery of “new fundamental underwater force”?

I read this article Discovering a new fundamental underwater force which describes the discovery of the mechanism that causes particles in stratified fluids, e.g. the oceans, to move towards others ...
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Guoy method derivation, or, how not to break math?

I start from $d\vec{F}=\nabla(\vec{m}\vec{B})$, $\vec{M}=\frac{d\vec{m_i}}{dV}$, and $\vec{M}=\frac{\chi_v}{\mu_o}\vec{B}$. I write out the definition of the force, determine we're only interested ...
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1answer
41 views

Distance between laser diode and photodetector

I have a laser diode with a wide divergent elliptical beam (angles: 57°-13°). If I want to use a light detector with 50mm diameter, how can I estimate the distance at which I can put the LD from the ...
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2answers
129 views

Why is the the positively charged electrode referred to as the anode in this apparatus?

In this image taken from the manual of the NaRiKa/Nada Scientific EM-4N e/m apparatus, you can see that the positively-charged electrode (the one electrons are attracted to) is labeled "anode." This ...
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1answer
39 views

How often do positrons appear in a typical Wilson cloud chamber?

I would like to know a rough estimate of how often positrons appear per meter cubed per second in a typical Wilson cloud chamber based off of your experience. I'm interested in the same quantity for ...
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1answer
45 views

Why are error bars used instead of error blobs or error rectangles?

In reporting experimental results, it is common to use error bars to communicate uncertainty in measurement of the quantity represented by the y-axis. But, usually, there would also be uncertainty in ...
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30 views

Double slit detector properties

As the only way for me to follow discussions about double slit phenomena is through this site and some videos, I must be clear that I don't know how an actual double slit detector looks like and how ...
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1answer
47 views

How to subtract background from many spectra which were taken with different background intensity?

I have two spectra, a spectrum of background signal (let's call it Reference) and measured spectrum consisting of searched signal and background signal. The searched signal is a peak/s with various ...
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49 views

How can I create gamma rays with energy >2MeV?

I have been exploring pair production (electron/positron) using gamma, and with a Cobalt-60 source this is easy enough. That's just the problem, though. I'm looking for a challenge. I want a stream ...
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2answers
40 views

Errors in measuring devices

I have a question regarding what we mean when we report the error in any measurement. Let's say I have a measuring scale which has markings in mm. Therefore any measurement I make has a limit on the ...
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1answer
94 views

How does a yellow colour filter work in the sense of RGB colour model?

I learnt after reading How do color filters placed in front of a light source,change the color of light that passes through? colour filter work by permitting only one colour and absorbing or ...
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1answer
56 views

What happens when we change the order of colours in Newton disc?

In Newton Disc, different colours constituting the visible region of the electromagnetic spectrum are arranged in the same order as they appear in the spectrum (increasing/decreasing order of ...
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1answer
281 views

Should damping ratio increase or decrease with increase in mass?

I'm currently doing a small project in college for structures being damped. We're adding weights to a structure and measuring the damping affect. We've calculated the damping ratio and coeffecients, ...
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1answer
64 views

Changing hot-filament SEM electron source into field-emission one

MOTIVATION: The resolution of scanning electron microscope (SEM) images is limited by multiple factors, one of them being relatively low electron-beam current density emitted by cheap tungsten ...
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1answer
39 views

Choosing $Z$ particles from a simulator results

I am pretty new to particle Physics. As one of my first projects, I have run a simulation using MadGraph and Delphes. From the simulator result, I am trying to find Z particles produced in the ...
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39 views

Actual data of single photon double slit experiment

I am interested in mapping the actual location of single photon impacts in a double slit experiment as a time series. In other words, I would like three data points for each photon measurement - the ...
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1answer
35 views

Angular Velocity of a point on a deflated tire (gyroscope measurement)

Before I do the experiment, I am a bit confused about the expected signals provided by a 3-axis gyroscope (angular velocities vs. time) mounted on the edge of a (slightly) deflated car tire when the ...
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21 views

VMI image analysis

I used VMI for the photodissociation of O2 and I wonder how I can correlate the radius with the actual velocity of the fragments. Thanks a lot!
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2answers
92 views

How do we know that temperature is the random motion of particles of matter?

It is written in many textbooks that heat is the random motion of particles but no text book mentions that how do we know that heat is the random motion of particles
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1answer
266 views

What is the purpose of holes in the sound box of a sonometer?

The following two images of Sonometer, a device used to study the laws of transverse vibrations of a string, show that the sound box (wooden part of the apparatus) consists of two or three holes: ...
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28 views

How (if possible) can I measure a pulsed signal with a lock-in amplifier?

I am trying to simulate free-field acoustic conditions using a pulse technique - i.e. send an acoustic pulse from source to receiver, and measure only the initial response, cutting out all reflections ...
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1answer
83 views

Density frequency height uncertainty in histogram

I have a set of $ N=150 $ measurements of the acceleration of a falling mass: $$ X=\{x_i | i = 1,...,150\} $$ I have to plot this data in a histogram with fixed number of bins, let it be $N_{bin}$...
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1answer
24 views

How would you measure static electric charge in the wild?

In the early 1990's I saw an extreme example of static electricity. It was in a university library. I would walk in and walk normally for 5 minutes. Then when I tried to walk out, if I touched the ...
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101 views

Is it possible to create an atom, proton, neutron and electron?

I know that it is not possible, however, this thought keeps me awake and make me thinks a lot. Is it possible to create an atom artificially from free protons, electrons and the neutrons??
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1answer
97 views

Frequency drift of a tuning fork

I bought a cheap tuning fork A 440 Hz. I measured its frequency to be 440.9 Hz. Since I bought it just for fun, not that I needed a precise frequency reference, I decided to screw around and to try to ...
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2answers
43 views

Calculating uncertainty in a fitted model

I am working on a project that requires the measurement of the Verdet constant of a material by observing a phase shift in the cosine squared model provided by Malus's law. I have recorded the ...
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1answer
36 views

Beam profile of alpha particles

Reading about the Rutherford gold foil experiment, I came across this paper (Emily P. Wang, 2004). In section 4, the alpha particles' beam profile (count rate as function of angle) is found to be "...
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28 views

Use of X-rays in Oil Drop Experiment

Why did Millikan use X-rays and not any other electromagnetic wave to ionize the oil drops ?
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29 views

Why does an explosion on the surface remove ground underneath it, creating a crater?

Why do bombs exploding on earth surfaces typically create a crater? An explosion on the surface of a compressible ground creates a depression by compressing the ground. An explosion on the surface ...
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1answer
175 views

Why does the beta energy spectrum of Sr90/Y90 only show the peak for Y90?

Im currently working on an experiment where I am investigating the energy distribution spectrum of Strontium-90 and Yttrium-90, which are two beta-minus decays, with the help of a quarter-circle ...
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0answers
32 views

Why do compressed spectra produce soft decay products?

Compressed spectra, as produced by BSM models like the mUED (minimal Universal Extra Dimensional) model and the MSSM (Minimal Super Symmetric Model), are associated with soft decay products. The ...
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How to find true north for calibrating angular position of scientific equipment?

I am in the midst of installing a scanning mini micro pulse LIDAR, which would be purposed to measure the cloud height profile of the atmosphere. The cloud height profile will be matched with ...
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0answers
17 views

Charge neutrality during hole cyclotron resonance measurement

In the '50s '60s '70s, the cyclotron resonance experiments had a golden age. Many by now well-known material (Si, Ge, InSb) was characterized at this time. For cyclotron resonance, it is necessary to ...
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1answer
47 views

Why do antinuetrinos get emitted during beta decay?

Why do antinuetrinos get emitted, during Beta Decay? Can the existence of them be discovered mathematically (and if so, how?), or is their existence only proven, via empirical means?
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21 views

Basic concept of interaction probability

In William R. Leo's book(Techniques for Nuclear and Particle Physics Experiments) I could not understand the following: $P(x)=$probability of not having interaction after a distance $x$ $w \delta x$=...
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32 views

Aluminum Activation

StackExchange. Long time reader, first time asker. So I'm trying to calculate a prediction for a radiation spectrum of Activated Aluminum, an example of which is shown below. [The Paper I got that ...
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1answer
33 views

Clarification on error and uncertainty propagation

This is a purely fictional example: suppose I want to find the voltage drop across a resistor $R$ where a current $I$ flows. My resistance supplier established a tolerance of 5% for $R$, so I know ...
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0answers
49 views

How do you measure short distances <1m accurately to 4 significant figures?

I'm measuring the distance between the two cords of a bifilar pendulum and its currently the lowest significant figure data I have. I considered wrapping a string around the two cords and halving the ...
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4answers
258 views

What causes the spirals to be inward in the bubble chamber images?

My understanding is that the circular paths are caused by the action of the Lorentz force on the electrons and positrons. However, I'm not sure why the circular paths are going inward. I have two ...
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1answer
181 views

Nobel Prize in Physics 2019 on exoplanets and Hot Jupiters

The 51 Pegasi b, discovered by Didier Queloz and Michel Mayor is classified as a hot Jupiter and not considered to be a star. I had read a bit about the minimum mass necessary for being a brown dwarf ...

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