# Tagged Questions

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

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### How Does Silicon Surface Barrier (SSB) radiation detectors work?

I'm dealing whith some old detectors (about 1980) called Silicon Surface Barrier, searching online I've seen that they consist on metal-semiconductor(Si n-type) junction (schottky diode) and in one ...
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### Polarized Coherent Beam Hits a Polarizer Off-Polarization Angle While Varying Distance?

Just wondering about an experiment that should be easy to perform on an optical bench: A coherent beam is polarized. It then hits another polarizer which is set to permit a polarization angle off ...
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### Optics to correct focal distance across a plane

I have a laser beam which is focused to a point at a certain distance. I'm then going to use a galvanometer to scan that beam across a plane. Obviously, as the beam scans across the plane, the ...
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### Logarithm of the voltage of the inductor in RL circuit experiment is nonlinear with time

I performed an experiment about the RL circuit, with following circuit: (I used the PASCO RLC circuit lab.) By Kirchhoff's voltage law, (denoting the emf of the signal generator $\mathscr E$, ...
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### Finding the appropriate fitting function for a coherence length measurement

I'm studying Coherent Optics in Experimental Physics, and I intend to determine the coherence length of a two beam interference. To do that, I used an He-Ne laser, a Michelson interferometer and a CCD....
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### Excess corn starch in a non-newtonian fluid

I'm currently performing a high school experiment regarding non-newtonian fluid. And as a further exploration, I am aiming to figure out whether excess corn starch in the solution will cause a ball to ...
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### Heat transfer with a small airgap - conduction v convection v radiation

I have a transducer approx 25mm dia x 25mm length which will sit inside a brass casing, but stood off from the walls by around 0.5mm. Obviously the brass is a far better conductor than the plastic of ...
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### Why isn't every magnetic neutron scattering peak a nuclear scattering peak as well?

Neutron diffraction is a well-established technique for determining the magnetic unit cell of magnetic materials. The idea is that nuclear scattering gives you peaks that correspond to the crystal ...
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### Explanation of two slit experiment [duplicate]

Whilst going through 'a brief history of time' ,I faced difficulty in understanding the two slit experiment. How can individual electrons cause fringes?
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### Interpolating experimental data correctly (limited model knowledge)

I have data which I know follows a function $y = f(x)$ such that it is quadratic i.e. $y =\alpha x^2$ for some $\alpha$ when $x\rightarrow 0$ and $y = \beta x$ for large $x$. The data itself has ...
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### The lightest photon ever detected

Wiki says that a photon of mass equivalent to $10^{-62}$ kg has been detected: 10×10−62 kg Mass equivalent of the energy of the lightest photon detected [citation needed] this equates to a ...
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### Why does the shock in viscous flow occur sooner than non-viscous one?

Why does the shock in viscous flow occur sooner than non-viscous one? If we want to discuss about drag, which one has bigger drag? This figure may help.
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### Role of Cavity Resonators in continuous wavelength-electron paramagnetic resonance(CW-EPR)

Why is it necessary to place the sample in a cavity resonator for obtaining EPR spectrum in CW-EPR? What role does a cavity resonator play in a CW-EPR spectrometer?
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### Finding the geometric efficiency of a cylindrical Marinelli beaker

I want to find the geometric efficiency of a cylindrical marinelli beaker filled with soil to perform gamma spectroscopy, so essentially the ratio of rays that pass through the detector to the overall ...
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### Why Flow meters are some times showing -ve fluctuating Values in Pressurized Pipe lines [closed]

In our Underground Water reservior we are pumping water by Hydro-pneumatic pumps to maintain same pressure till last connection. in order to measure the flow we have installed precise electromagnetic ...
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### Thermodynamic degrees of freedom of a wire

In Equilibrium thermodynamics by C.J Adkins he mentions an example about degrees of freedom of a thermodynamic system -- Very often for a simple system it is possible to say immediately that how ...
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### Why did it take so long to find the Higgs?

The $W$ and $Z$ boson took a long time to be discovered because they were so heavy; we couldn't produce them in a particle collider until the 80's. But the Higgs boson isn't that much heavier than the ...
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### How are optical lattices created, and how big can they be?

I am asking about the basic concept and the schematics of the laser configuration. How are atoms forced to stay in optical lattices? What lasers (power, wavelength, etc.) are used, and how are they ...
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### Slackline tangling

This question is about random formation of knots in a systematically tied rope. I will give some background, hope that does not make it off-topic. In climbing (and sailing) one has to store very long ...
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### Magnetically shielding an actuator

We need to magnetically shield a solenoid that activates this valve (shown below) Just slipping a mild steel cap over the end does not do the job, nor appears to have any screening effect at all. ...
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### Real-World Example for the Horizontal Spring-Block Oscillator

I am wondering whether there exists a spring that behaves like those shown in a multitude of physics textbooks, where a mass stretched/compressed to a certain point oscillates back and forth in some ...
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### How to observe neutrinos?

I know that neutrinos are the weakly interacting particles[possibly zero mass] that can pass through matter without any effect which makes them very difficult to detect. But I have heard that they ...
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### Physics of tagging at B factories

At some B factories, mesons carrying $b/\bar{b}$ quarks are created by $e^-e^+$ collisions at $\gamma(4S)$ resonance. $\gamma(4S)$ decays into antisymmetric wavefunction given by  \frac{1}{\sqrt{2}}...
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### Is it possible that viscous flow has a higher lift to drag ratio than inviscid flow?

I have a code for airflow around an airfoil. When I compare viscous and non-viscous flow at the same Mach number for a cruise, viscous flow has a higher lift to drag ratio than non-viscous flow. Is it ...
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### What direction are the decay particles of muons emitted in?

If I were to run an experiment where I could measure the neutrino as well as the positron emitted when a muon decays, what direction should i be looking in?
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### Sine wave in my residuals graph [closed]

We had a physics experiment where we should have had a linear relation between 2 measured values, we got a pretty good fir however our residuals plot has a kind of a sine wave behaviour. We were told ...
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### Detection of closed timelike curves (CTC)

I have a question. Are there any methods for detecting CTC? Is there a possibility of designing modern physics experiment in order to confirm / refute the possibility of CTC at any given time in a ...
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### Lab equipment - where to start [closed]

I've started to seriously study physics on my own, using various resources such as edX courses etc. However I believe that carrying out experiments will help me gain a deeper understanding of the ...
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### Michelson interferometer finding $\frac{\Delta \nu}{\bar \nu}$?

Let us say we send light with wavenumber $\bar \nu \pm \frac{\Delta \bar \nu}{2}$ through a Michelson Interferometer. Using the intensity at the center of the interference pattern $I(x)$ (where $x$ is ...
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### What is the easiest way to prepare a Glauber coherent state? [closed]

Without using a laser source. Can you, for example, create a coherent state by filtering another light source (incandescent light bulb, LED, etc)?
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### Printing zone plate with laser printer

I tried to print my own zone plates on transparent plastic with laser printer with this generator. I prepared a lot of plates with different settings - focus from 4 to 60 cm, 3 wave lengths, etc. Yet ...
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### Spherical Harmonic fitting excess polar magnitudes

I am trying to fit an expansion of spherical harmonic functions to a dataset distributed over the surface of a sphere using the least squares method. Each data point is in terms of $(r,\theta,\varphi)$...
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### Are residuals supposed to have error bars?

Hopefully I'm asking this in the correct section. So I've got a graph with a linear trend of data and a best fit line plotted. The data points on the main graph obviously each have their own error ...
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### To what degree the probabilistic nature of quantum mechanics is tested?

I am not sure the question is well posed, what I mean is sort of an experiment in which one extracts some random, say, uniform distribution out of a quantum processes, and tests to what degree that ...
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### Why so much electric charge?

I'm working on the Millikan experiment using the following apparatus: http://www.unitedsci.com/product-catalog/millikan-oil-drop-apparatus-0 when I compute the value of charge of the oil drops, the ...
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### Michelson Morley experiment? [closed]

Its not that I question the conclusions reached concerning the Michelson–Morley experiment, however I would like to know how the following issue was addressed please? If I could pass bob through a ...
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### Definition of atmosphere unit and relation to temperature and gravity

I've seem sometimes the atmosphere unit for pressure be defined so that $1\ \mathrm{atm}$ would be the mean atmospheric pressure at sea level. I've seem on the other hand the following definition: ...
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### Choosing curves in data fitting [closed]

I have got a series of data points in experiments. And now I am trying to do some fitting job. What kind of curve should I select for this if I don't know what the exact expression is?
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### How to measure an image's contrast?

I'm studying Fourier optics and Interferometry and I intend to determine the contrast of an image using computer software. My teacher of Experimental Physics didn't tell me how to do it, and so, I'm ...
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### How is Spin experimentally determined?

I know what spin is and how theories determine it for particles. What I don't understand yet, is how people, through experiments and data analysis or whatever, reach to confirm/say that the $X$ ...
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### Is the probability current an observable?

Is the probability current in Quantum Mechanics an observable? If so, how can it me measured (directly or indirectly)?
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### Ideas for extending Muon-Life-Time experiment?

Background: I'm teaching a lab experiment for measuring the Muon lifetime. The experiment is a big tube of scintillator attached to a PMT. The muon entering the scintillator generates a reading in the ...
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### Difficulty in dissolving scotch tape

The scotch tape peeling of graphene is the classical way to do it. But I am having difficulties in dissolving the scotch tape gum and it is giving noise in the Raman signal. How can I transfer the ...
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### Finding natural linewidth's

I want to check whether my fit parameter for the width of a Lorentzian fit on my digital spectroscopy data for Helium (the 5875 Angstrom line) is what you would expect from the uncertainty principle, ...
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### Inconsistencies in data: magnetic field in solenoid

In lab for our Calculus based Electricity and Magnetism course we are, for one portion of our lab, exploring the relationship between increasing the number of loops in a solenoid and the magnetic ...
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### Ultrasound Transducers and Simulator [closed]

Presently I am working on Underwater Acoustic Wireless Transmission. I desire to measure water parameters at the bottom of the surface of the water and then pass it to the water surface using ...
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### Where can I find Lorentzian values for the width of spectral lines for fitting XPS data?

I'm trying to curve fit my XPS data. I would like to start with known parameters to have an idea. Does anyone know of places the Lorentzian (and even the Gaussian) of elements is located?
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### What is the Current Status of Measurement of the Gravitational Mass of Antimatter?

My current understanding is that it's generally expected (and has been predicted) that antimatter will fall down and not up in earth's gravity. But I haven't been able to locate any definitive ...