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

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29 views

Galileo's pendulum and any references

In some texts about the simple pendulum we use to see references about some "experiments" Galileo Galilei did realize and whereby he found some important results, including that the period of the ...
3
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1answer
135 views

How to read numbers reported in this LIGO paper?

I am not sure how to read the numbers in this excerpt from the abstract of GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence: Are the +/- small ...
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1answer
51 views

High $p_T$ and high $Q^2$ in deep inelastic hadronic collisions

When reading about high energy collisions (for example proton-proton collisions at LHC), I always find the relation $Q\sim p_T$, which, for me, is hard to demonstrate. Moreover, I found statements ...
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0answers
33 views

Cheap DIY Zernike-Phasecontrast: Optical Thickness of a inkjet/laser printed contour for phasering? [closed]

Rough guess: Optical Thickness of a inkjet/laser printed contour? Edit I was wondering if there is any research regarding the refractive index and the height of an inkjet or laser printed contour?  ...
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0answers
18 views

Comparison of electron deflection tube and Hall effect

Consider an electron deflection tube (something like this: http://www.ld-didactic.de/documents/en-US/GA/GA/5/555/555624e.pdf). Suppose you apply a magnetic field perpendicular to the screen. Then ...
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0answers
20 views

Liquid-vapor saturation curve

I am trying to draw the saturation curve for liquid-vapor region, but I don't have the exact equation. Can someone help?
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0answers
12 views

Why can we extract the oxidation state from XPS and XANES but not from XRF or EDX?

To my understanding it is possible to extract information about the valence/oxidation state of an ion in a material by using X-ray photoelectron spectroscopy (XPS) or X-ray absorption near edge ...
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0answers
106 views

A theoretical model for evaporation occurring when wind is blowing over the surface of water

I've recently done an experiment in which I was studying the variation of the cooling rate of hot water in a draft (wind). The air was blow directly over the surface of the water (kept in a ...
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1answer
45 views

why do microscopic cracks happen?

2 weeks ago i asked a question about " Gas permeation through solid metal? " i have got a very good answer here .but microscopic crack was mentioned in the answer. i searched in Internet but i didnt ...
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0answers
16 views

Cathode Ray Tube: Nonuniform Magnetic Field

For an experiment, I found out that the charge to mass ratio of electron was 1.91x10^11 C*kg^-1. So, I overestimated from the theoretical quite a bit. I used a cathode ray tube with Helmholtz Coils ...
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0answers
26 views

Scanning Electron Microscopy on a smaller scale

Is it possible to sufficiently focus a ~1nm beam of electrons into a sample chamber in less than 10cm of vertical space, therefore reducing the volume of the entire vacuum chamber, and subsequently ...
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1answer
42 views

What do the terms “offline” and “online” refer to in the field of high energy physics data analysis?

The title says it - I've encountered these terms several times but have never found an explanation anywhere. An example of use is this ATLAS note. If I may hazard a guess: Data rate is high at the ...
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2answers
60 views

How to calculate energy loss in a rotating shaft?

Please help me with proper formula for below example. Imagine a rotating shaft 'X' with 2 gear wheels 'a' and 'b' of same dimensions. If energy applied to gear 'a' on the shaft through source A ...
3
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1answer
40 views

Why does a CfBe neutron source not exist?

Sources such as AmBe take advantage of Beryllium's $(\alpha,n)$ process to produce high energy neutrons. Sources such as Cf utilize spontaneous fission. Why not combine the two? Such a source would ...
2
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1answer
54 views

GR Verification for a Charged Black Hole

For a charged ($Q$) rotating ($L$) mass ($M$), the Kerr-Newman equations give the angular deflection of light. Has there been observational verification (I would prefer to use only the angular ...
0
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1answer
57 views

How are the standard model and the Higgs boson actually confirmed experimentally in practice?

This is my mental picture on how we can make predictions from a theory (I'm not a physicist so this might be quite wrong) : Typically, we solve a partial differential equation (analytically if we can,...
2
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1answer
33 views

What will happen if we establish a physical connection between ground and ionosphere?

https://en.wikipedia.org/wiki/Ionosphere The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth, stretching from a height of about 50 km (31 mi) ...
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1answer
32 views

Verify Faraday's law of induction [closed]

I need to design a procedure for an experiment to verify Faraday's law of induction. I'm given: A Helmholtz coil of radius 15 cm Three plastic spheres of radii 1 cm, 1.5 cm, and 2 cm. A spool of ...
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3answers
34 views

How to determine the concentration and sign of the charge carriers in copper

I need to design a procedure for an experiment to determine the concentration and sign of the charge carriers in copper. I'm given: A slab of copper 2.0 mm thick, 1.5 cm wide, and 4 cm long One very ...
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0answers
33 views

Effect of shielding on a miniature Helmholtz coil

So a bit of background... I'm a university graduate student with primarily digital signal processing and embedded experience. However I've managed to get myself involved with a project that requires ...
0
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1answer
33 views

Basic high school physics question, on measuring voltage from CRO screen:

My textbook says 'this represents a voltage that varies from +300mV to -300mV. If this voltage were measured using a meter a value less than this would be displayed since the meter gives an average ...
0
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1answer
35 views

How to interpret these gravitational lensing data?

The data I am trying to understand this gravitational lensing data in the link above. However, unfortunately I don't have an extensive knowledge in physics. Could someone please tell me what each of ...
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0answers
22 views

How is a frequency comb used to stabilize other lasers?

So I am currently in the process of writing my bachelors thesis which partly concerns frequency combs. I have read that some of the applications is: Optical measuring tool. (by detecting beat-note) ...
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2answers
74 views

How are laws proven in general?

This may be a bad question, but what are the ways that laws are proven? I would expect that some ways would include by proving them mathematically or through experimentation. My biggest question about ...
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0answers
150 views

What is the significance of the possible new 17-MeV “protophobic X boson?”

Krasznahorkay et al ...Possible Signature of a Light, Neutral Boson published results in 2015 of a possible new particle at 16.7 MeV+/-0.35. The researchers suggest "such a boson might be a good ...
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0answers
27 views

High pressure deformation of metals

Does copper undergo elastic recovery after being exposed to high pressures (above 30 GPa in a diamond anvil) at room temperature?
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2answers
74 views

Muon lifetime determination

My colleagues and I performed several experiments to determine the lifetime of the muon (from secondary cosmic rays) using scintillator detectors coupled to multi-channel analysers. The results ...
0
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1answer
53 views

Are pure Dirac fermions (electrons, quarks, …) allowed to have effective Majorana mass?

Charged particles such as electrons and quarks are not allowed to have a hard Majorana mass (see here). With 'hard' I mean an explicit mass term in the Lagrangian which would break the corresponding ...
47
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4answers
4k views

Why does LIGO do blind data injections but not the LHC?

The LIGO group has a team that periodically produces fake data indicating a possible gravitational wave without informing the analysts. A friend of mine who works on LHC data analysis told me that ...
2
votes
2answers
75 views

Experimental confirmation of the textbook explanation for local entropy reductions

Clarification: In my original wording of this question, regrettably, I did not make it clear that I am interested in the the Boltzmann/Gibbs/statistical (BGS) interpretation of it, as opposed to the ...
4
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2answers
140 views

Why do we learn only two computations, cross sections and decay rates, in such a fundamental theory as QFT?

When I learned Newtonian mechanics I found a vast variety of computations that I could do and that was so interesting. And it was so when I learned Maxwell theory. When I started learning QFT I hoped ...
2
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2answers
60 views

Why don't reflector telescopes place their reflectors at an angle?

To avoid placing a secondary mirror in front of the objective mirror, why not tilt the objective and design the eyepiece in such a way that comatic aberration is minimized?
3
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1answer
41 views

How can I determine whether balloons inside a balloon are filled with the same gas?

We recently awarded ourselves some helium balloons to celebrate something, and they came with about a dozen little balloons inside, filling it to just under half way. I was discussing with a ...
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1answer
88 views

Measuring tides in a swimming pool

The tidal range of a perfectly fluid inertialess ocean on the Earth (taking into account lunar tides only) is approximately half a metre: this is the range between "high" and "low" points of an ...
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1answer
35 views

Young's modulus and geometry of test material

When measuring Young's modulus in a material, does the geometry of the material actually matter? I have seen several references recommend that I use cylindrical pieces. But, wouldn't the tests work ...
8
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2answers
156 views

Can the question of a gravitationally accelerated charge radiation be tested experimentally?

I know that the question of radiation from a gravitationally accelerated charge has been discussed extensively at Does a charged particle accelerating in a gravitational field radiate?. Yet the ...
0
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1answer
38 views

Which experiments of harmonic generation at low frequencies preceded Franken's SHG?

In The Principles of Nonlinear Optics by Shen, he says that the generation of harmonics at low frequencies were long-known before Franken did SHG in the optical range. Franken's idea was simple. ...
1
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1answer
30 views

Systematic+Random Uncertainty for velocity measurement

I have a question regarding systematic and random uncertainties. I have to measure the mean value of a velocity measurement in flow field at a point. I've recorded say 1000 samples in time, which I ...
46
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3answers
3k views

Why are LIGO's beam tubes so wide?

Gravitational wave detectors and particle accelerators have at least one thing in common -- they require long vacuum tubes through which a narrow beam is fired (a laser in the gravitational wave case, ...
1
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1answer
34 views

Can vernier scale ratio be less than 1?

I came across a question (See Image) that states about two vernier scales The first vernier scale is the top-most figure in the image: It has 10 vernier scale division equal to 9 main scale division ...
1
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1answer
30 views

Heat loss by radiation reference

In our lab practice, we measured the rate of heat loss of a copper plate in atmospheric pressure and the rate of heat loss of the same plate in high vacuum ($\sim 10^5 torr$). So all I could find for ...
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0answers
12 views

Transverse momentum [duplicate]

I'm having an introduction on detector systems in particle physics. The sources I read constantly talk about the measurement of "transverse momentum". However, I cannot find a definition of what is ...
5
votes
1answer
53 views

Optical Retroreflectors: How Are the Faces So Accurately Righted?

This question is about Optical Retroreflectors (corner cubes) and how the extreme precision in their manufacturing is achieved. I suspect there is interesting basic physics involved, which is why the ...
1
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1answer
40 views

Why surface tension behaves so differently?

When a needle (or any other object) floats on water, its acting upwards balancing the gravity. But when an object (or may be a needle suspended in water) submerged in water, it acts downwards. ...
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0answers
30 views

Four point probe method under liquid nitrogen

I was trying to measure the resistivity of the YBCO superconductor (but not like a resistivity- T diagram, but only at liquid nitrogen boiling point), so I needed to put the sample in thermal contact ...
0
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0answers
16 views

The distribution of net charge in the Millikan oil drop experiment?

What is the distribution? Of course it depends on the concrete setup. But, what is the typical value? The concern is that, if the distribution is peaked at, say 1000, it would be very difficult ...
1
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2answers
62 views

Lamina Pendulum Experiment help

I've been tasked with researching ways to find the gravitational acceleration g and its uncertainty together with the moment of inertia and and the moment of inertia's uncertainty. I have figured out ...
0
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0answers
21 views

LIGO Gravitational Wave Discovery and Gravitons [duplicate]

Now that gravitational waves have been detected, how hard will it be to detect a graviton? Will the equipment have to be more sensitive or are the difficulties more complicated than that?
3
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2answers
75 views

Best way of calculating average acceleration in lab experiments

I am doing a lab experiment that works as follows. An object moves along the $x$ axis with an initial acceleration and then moves with a pretty constant velocity that may slightly vary within $20\%$ (...
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0answers
41 views

What is space charge Capacitance of diode?

Most of the books say that $p$-type and $n$-type materials of diode act as parallel plates of space charge capacitance were as the depletion charges (uncovered) act as dielectric. Then why do these ...