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Questions tagged [experimental-physics]

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

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How did Coulomb measure charges?

I was studying some Electrodynamics when suddenly this question popped into my mind : The whole of Electrodynamics is based on the Coulomb's Law. There is no derivation of this law because it is an ...
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1answer
53 views

Has the “osmium spheres” gravity example ever been done?

Calculating the motion of two dense spheres (in a frictionless vacuum) due to gravitational interaction is a classic physics problem that has come up numerous times. Has any real-world space mission ...
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0answers
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How is it possible that unrolling scotch tape in a vacuum causes X-rays? [duplicate]

A fun kind of question... In 2008, researchers at the UCLA's Department of Physics and Astronomy found that unrolling of scotch tape in a vacuum caused X-rays to be created. First, energetic ...
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1answer
65 views

Doesn't assuming “equal probability” create a conflict of interest with science? [duplicate]

What is the right scientific approach when face with an unknown sequence? My understanding is: Null hypothesis = It is nothing but noise. It is random sequence generated by equal probability without ...
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1answer
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Can any body suggest me a set up that I can build it up to study the surface roughness of transparent polymeric fibres? [on hold]

I need to study the surface of nylon-6 blank fibres with a thickness of nearly 40 micrometre. I work in optics lab with many optical components such as beam splitters, lenses, mirrors, etc; can I ...
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1answer
23 views

Why is the transverse Doppler shift “difficult to measure”?

I'm currently reading a book on optics, and have encountered a curious section: $$\nu = \nu'\sqrt{1-\frac{u^2}{c^2}} = \nu'\left(1-\frac{u^2}{2c^2}+\ldots\right)$$ This is the formula for the ...
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3answers
77 views

Particle accelerators and the amount of radiation they emit

Do particle accelerators emit a lot of radiation? If they do, can someone give me a rough estimate of how much? I'm also curious as to what kind of radiation they give off.
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0answers
65 views

Why do we believe local gauge invariance (that tells us photons are exactly massless)? [duplicate]

There are experimental upper limits on the photon's mass, but they are finite. I heard that the reason we know that photons have exactly zero rest mass (and thus travel exactly at the universal ...
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0answers
34 views

Why does a cooking thermometer show different temperatures when touching the container of a liquid?

I have a cooking thermometer that looks like a 10-15 cm long metal rod, that can be inserted into the thing you want to measure the temperature of: When inserted into boiling water, I observed that ...
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3answers
78 views

Can this be considered the Newton's rings?

It can be made by pointing a laser pointer directly to a mirror at low angle and observing the reflection behind the laser pointer. No convex or concave lens needed unlike the Newton's ring experiment ...
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1answer
67 views

Experimental tests of Schrodinger evolution, position distribution, in square well and other simple systems?

Have the energy eigenfunctions in position space ever been experimentally tested for the simplest system undergraduates encounter when learning quantum mechanics, the square well? If not, what is the ...
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20 views

Which device to measure UV lamp wavelength with high precision

Which techniques and devices are able to measure the wavelength/frequency of a UV lamp within the wavelength range of 50nm - 300nm? Is a VUV Optical spectrometer the right device for this?
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2answers
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what are the sources of energy loss for a ball rolling down slope?

I am experimenting in lab with an iron sphere rolling down a smooth aluminum ramp. The final velocity is smaller than the one predicted assuming energy conservation (see calculations below), which ...
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0answers
16 views

Magnetic force and work done [duplicate]

If magnetic force do no work at all then how do magnets attract or repel each other?
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0answers
22 views

The droplets size of different liquids?

Does the size of a droplets depends on the size of the opening of the burette or pipette, would increasing the rate by which the droplets are falling would change the size of the droplets? Or does ...
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1answer
25 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 ...
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0answers
28 views

Rubidium as hydrogen-like - optical pumping

Rubidium is an alkali metal with only a single valence electron. I read in a lot of optical pumping papers that this enables us to approximate it as hydrogen-like. I am interested in the ...
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0answers
12 views

Frank Hertz I-V curve

Now my question is assume here gas to be hard balls with no possibility of inelastic collisions and electrons are emitted from a cathode and they reach anode through this soup of atoms. Since ...
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0answers
19 views

What are the dynamics of a rope wrapping around a pole of given radius?

Suppose we drop a mass m from an initial angle $\theta_o$ connected to the pole of radius r with a rope of initial length $l_o$. As the system is released, the rope wraps around the pole, decreasing ...
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1answer
67 views

Optimal pump wavelength for frequency doubling in periodically poled media

Background I am currently working on achieving second harmonic generation (SHG) in periodically poled lithium niobate (PPLN) using a 1560 nm pump laser. PPLN makes use of quasi-phase-matching of the ...
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0answers
30 views

Experimental justification for modelling electron as point instead of charged shell? [duplicate]

Down to what size is there experimental justification for modelling the electron as a point like particle without volume? Asked in another way, at what size scale would it be more correct to model the ...
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1answer
15 views

How position of source affects YDSE interference? [closed]

I was wondering that how position of source of light affects YDSE experiment? I know that path Difference of light after the slits is the reason for YDSE interference pattern observed, but how path ...
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2answers
28 views

Do you have an idea for two easy experiments to measure the coefficients of static and sliding friction of a rope wrapped around a steel rod?

I'm researching a phenomenon dependent on the Capstan/Euler-Eytelwein-Equation. To model a simulation, I need the friction coefficients. I came up with the idea of hanging one mass $m_1$ on one side ...
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1answer
50 views

How can you use tensors in theory of elasticity? [closed]

I am interested in physics and Icame across the usage of tensors in elasticity. How do you do that? How can tensors be useful?
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1answer
60 views

What is the scientific method for finding a theoretical explanation for experimental data?

Say you observe some effect that you did not anticipate in one of your experiments. You have checked the experimental setup and you're sure it's not just a systemic error but an actual measurement of ...
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0answers
31 views

What are common materials that absorb near infrared radiation?

I am running an experiment in my university lab where I want to compare with a sensor how much IR radiation gets transmitted in different scenarios. I need some (preferably common) materials that ...
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1answer
86 views

A basic question on Heisenberg uncertainty and experiment

I’m not a physicist or anything even close. But what I understand from the reason for the Heisenberg uncertainty is that the photon is changing the volecity/momentum when it hits the particle. ...
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1answer
42 views

A spinning pendulum [closed]

I just thought of a scenario : We rotate a sphere that is hanging from a string about vertical axis and then allow it to oscillate like a pendulum . Will its time period differ from a sphere ...
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1answer
23 views

Why does an ultrasound motion sensor not work for objects closer than 15cm away

A wireless motion sensor uses echolocation to determine the distance to an object. The distance to the object is calculated based on the time of flight between the ultrasonic pulse to the detected ...
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2answers
42 views

Role of motion in experimental results

This page contains:"If you are in a closed room on a ship sailing at a constant speed and the ride is perfectly smooth...[t]here’s no physical experiment you could conduct to tell whether you’re ...
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2answers
63 views

Do I force the intercept to zero when determining the coefficient of friction?

I have made these measurements of kinetic friction force vs normal force: I want to measure the coefficient of friction as the slope of the line. Unfortunately the line does not pass through $(0,0)$. ...
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2answers
45 views

What is the proper way to combine two different errors for the same measurement?

We did an experiment in the lab (regarding magnetic domain walls) that yielded some pictures that we later on analyzed and manipulated in Matlab (we took an RGB image made it into grayscale one and ...
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1answer
106 views

Time evolution of molecular signal from a laser-induced plasma - finding the right model for my data

I am looking at molecular emissions in laser-induced plasma plumes created in argon at reduced pressure (in the mbar range). To be precise, these are heteronuclear diatomic molecules that emit ...
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0answers
35 views

Is it possible to reconduct “The delayed quantum eraser experiment” in home?

The delayed quantum eraser was conducted by Kim et al. in 1999 with the use of BBO crystals, polarizers, detectors and so on. I believe some of these equipments can be found online kinda cheaply, ...
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0answers
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Is there a way to perfectly combine beams?

Given two mutually coherent beams (same wavelength, polarisation etc.) described by electric fields $\textbf{E}_{\textrm{1}}$ and $\textbf{E}_{\textrm{2}}$, is there a way to combine these beams in a ...
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1answer
22 views

Using a collimating lens for beam interference

If I have two beams of light which are incident on the same point of a collimating lens, will they emerge as a single beam and interfere? I've attached a drawing below: If not, what happens?
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1answer
38 views

Experimental Assignment of Electronic Transitions in Atoms (Grotrian Diagram)

Grotrian diagrams often taught in instrumental methods of chemical analysis to chemists. After a decade, I finally found the original book of 1927 by Grotrian "Graphische Darstellung der Spektren von ...
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1answer
73 views

Is quantum gravity even detectable? [duplicate]

Since gravity is several orders of magnitude weaker than the rest of the fundamental forces, the force of gravity acting on a single particle is almost *nonexistant. Since there is still a lot left ...
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1answer
49 views

Combining light of the same linear polarisation

Is there a way to combine two (coherent) beams that have the same polarisation and wavelength in a lossless manner such that the resultant beam has the same polarisation as the starting beams? I'm ...
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0answers
22 views

Interpretation of a CLs exclusion plot

I have some trouble with the interpretation of this plot. The plot on the right shows the CLs values for the SM Higgs boson hypothesis as a function of the Higgs boson mass in the range 110–145 GeV. I ...
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1answer
40 views

Oscilloscope measurement on primary coil changes secondary coil voltage

So I was measuring the induced voltage in a solenoid (air-core) with the primary solenoid being on the outside (parameters:$N_p=100$, $l_p=12.6cm$, $d_p=5.1 cm$, $N_s=50$, $l_s=6.3 cm$ and $d_s=3.1 cm$...
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1answer
157 views

How to test quantum mechanics?

In this paper, Testing quantum mechanics, S. Weinberg states that The problem is to know what to test. Usually we can get guidance on how to test a theory like general relativity or the standard ...
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1answer
63 views

Does the Vector Potential Coil and Transformer Violate Special Relativity?

"Vector Potential Coil and Transformer" by M. Diabo et al reports the induction of voltage by a time varying curl free vector potential. A refinement reported in "Vector-Potential Coil and ...
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0answers
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How to find the path of a cantilever beam's tip when it's bent?

I'm trying to analyze the harmonic motion of a hacksaw blade with one end fixed to the table. I'm trying to get an equation from Hooke's Law F = kx, but I'm not sure about how to calculate the ...
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0answers
25 views

How can I determine, in what extent the fit to experimental data is good in Matlab?

I have experimental spectrum in which y-axis is intensity values, and x-axis is frequency values. Int - array of experimental intensities (y-axis). w - array of frequencies (x-axis). I know the view ...
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1answer
35 views

Light source needed in colorimeter and a spectrometer

I've found myself doing some research to ascert the differences when trying to assess the colour of a given sample. I've found two main options, which are (1) a colorimeter and (2) a spectrometer. ...
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0answers
42 views

Why my cloud chamber won't work?

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 ...
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1answer
84 views

Why atomic masses are quoted with reference to an isotope?

Is there any fundamental reason why atomic masses are quoted with respect to a certain element such as an arbitrary C-12 isotope whose mass has been set to 12 unit exactly? Previously, chemists have ...
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1answer
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Why are there no coefficients of drag for cubes and cones of low Reynolds numbers

I am currently reading ''Fluid Mechanics-Fundamentals and Applications'' by Yunus A.Cengel and John M.Cimbala. I am currently reading about drag coefficients in chapter 11 and how it talks about the ...
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Hallwachs effect with positive plate

If I send light of a bow lamp onto a negativly charged zinc plate it discharges as expected from the hallwachs effect. However the same occurs if I use a positivly charged plate. This shouldn't happen ...