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Questions tagged [experimental-physics]

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

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0answers
12 views

How to check experimental data against a theoretical curve in python?

I am trying to check the agreement of a dataset against a theoretical curve, specifically a bandstop filter in an RLC circuit. I have generated a function which describes the curve we expect from the ...
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1answer
48 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 ...
9
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1answer
184 views

“Modern Presentation” of Observations on Phase Transitions

In the introduction of Introduction to QFT by Peskin and Schroeder, the authors write "we do not discuss the beautiful and varied experiments on phase transitions that led to the confirmation of field ...
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 ...
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0answers
35 views

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 ...
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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?
1
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1answer
118 views

RF-sputtering: where comes the target self-bias voltage from?

While learning for an exam, I stumbled over the following Question: According to Material Science of thin Films by Milton Ohring, "RF sputtering essentially works because the target self-biases ...
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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 ...
2
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1answer
278 views

What is zero order transmission spectrum?

In the paper The extraordinary optical transmission through subwavelenth hole arrays by T. W. Ebbesen it is shown at particular wavelength there is a peak observed in zero order transmission spectrum. ...
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1answer
97 views

Ways for undergrad to understand physics research? [duplicate]

I am a college freshman who is looking to research in a experimental physics lab this year. I am an engineering student and have taken basic Physics classes, but I lack the background knowledge to ...
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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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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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,...
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4answers
2k views

Is there experimental evidence that massless particles such as photons attract massive objects?

For instance evidence that a highly energetic laser beam attracts objects nearby? In the framework of Einstein's general relativity all energy curves spacetime and hence exerts an attraction, but my ...
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2answers
463 views

Calculating thermal conductivity with measured data

this is my first post here. I hope I do and format everything correctly. I was given a spreadsheet which was automatically created and filled by a Cone Calorimeter. The sheet contains the following ...
2
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1answer
26 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
35 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 ...
1
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1answer
51 views

Spectrometer Experiment

What happens if the results of observations(experiment) by the spectrometer on Helium light source spectrum there are only 3 colors (e.g yellow, green and blue), while the reference there are 5 colors ...
1
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1answer
189 views

How to calculate maximum stress that can be taken by an object simply

My goal is to calculate the amount of stress it takes for an object to fracture. I would like to conduct a three point bend test, without having to buy a machine for it. The object is a pig's fibula ...
9
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1answer
161 views

How does the “Look Else Where Effect” affect the chances of detecting a false diphoton excess at the LHC?

Back in December 2015, there was found a 750 GeV diphoton excess in both CMS and ATLAS at the same location with a significance well above $3\sigma$; a 0.13% chance of being false. However, there ...
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2answers
231 views

Cut-flow in experimental particle physics (offline analysis)

In experimental particle physics, when analyzing data from some experiment we require a baseline event selection by applying "cuts" on kinematic variables such as the pseudorapidity $\eta$, transverse ...
0
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1answer
225 views

Capacitance dependence on separation between plates

I know that the capacitance of a parallel plate capacitor is $C = \frac{\varepsilon S}{d}$. I am supposed to perform a linear regression to obtain $\varepsilon$, however it turns to be a quadratic ...
0
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1answer
33 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 ...
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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 ...
1
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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
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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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?
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2answers
212 views

Why is it that the refrigerators (ice houses) from long ago can't be reconstructed in modern times? [closed]

A long time ago (a couple of hundreds of years), people could make a refrigerator by applying a certain procedure with pieces of ice, harvested in winter, and other stuff. The ice hadn´t molten at the ...
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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 ...
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
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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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{\...
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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 ...
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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 ...
2
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1answer
87 views

Why my cloud chamber won't work? [closed]

let me briefly introduce myself, I'm a highschool student from Indonesia, I'm currently making a cloud chamber for my science fair project, I did what the videos on youtube told me, but for some ...
6
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1answer
246 views

What are the longest half-lives we can detect experimentally? What stops us going further? Are we trying to?

Xenon 136, apparently, has a half-life of 2.11×1021 years. This strikes me as a humongously long time to run an experiment, clocking in at about 11 orders of magnitude longer than the age of the ...
679
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20answers
231k views

Cooling a cup of coffee with help of a spoon

During the breakfast with my colleagues, a question popped into my head: What is the fastest method to cool a cup of coffee, if your only available instrument is a spoon? A qualitative answer would ...
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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 ...
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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1answer
129 views

Evaporation rate of water with forced convection

A steel pot (diameter 200 mm) is fully filled with water (2 kg of water) and the water is maintained at a constant temperature of 40°C by supplying heat from an electrical tabletop burner. Assume ...
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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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2answers
267 views

How is aperture stop determined for a microscope?

Here are the images, depicting the aperture stops of the objective and eyepiece, taken out from Carson microsopce. Though the lens diameter is large, there is a black disc with a hole used as an ...
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 ...
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 ...
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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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2answers
40 views

What's “bimodal” about BEC velocity distributions?

I was just reviewing some papers discussing Bose-einstein condensation, specifically "Creation of a Bose-condensed gas of 87Rb by laser cooling" by Hu et al., and I saw repeated references to the ...
0
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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 ...
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 ...
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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 ...