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

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2answers
21 views

A simple pendulum having a solid metal bob

A simple pendulum with a solid metal bob has a time period T. The metal bob is now immersed in a liquid having density one-tenth of that of the metal bob. The liquid is non-viscous. Now the period of ...
2
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0answers
17 views

How are LIGO mirrors cooled?

The recent LIGO announcement Observation of Gravitational Waves from a Binary Black Hole Merger has some technical details about LIGO. For example, LIGO is a modified Michelson interferometer. The ...
1
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1answer
39 views

What are the wave characteristics for the detected gravitational wave?

I'm curious to know what the amplitude and wavelength of the detected gravitational waves are? The paper mentions some characteristics of the detection event, but not what that means for the wave ...
1
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2answers
50 views

How does the $4$Km arms of LIGO measured so accurately?

The arms of the LIGO interferometer are $4$ Km long.Now,LIGO functions by measuring phase difference between two beams of light comming (as in Michaelson's Interferometer) to a sensitivity of ...
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0answers
22 views

Gravitational imaging

As the most recent discovery in physics suggested the gravitational waves are now scientific fact. My question is: If that's the case so is it possible in principle to make perfect 3d imaging of an ...
0
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0answers
13 views

Stokes law percentage error

I am supposed to find the % error in t , r and D this is for Stokes law to find the viscosity.I have tried to find the % error in t we used a stopwatch so I found the mean from my values for t and ...
4
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0answers
160 views

G4v Gravity Wave vs General Relativity vs LIGO Observation

CalTech emeritus professor Carver Mead produced an alternative prediction, to General Relativity, for gravitation wave observation which he published last year in anticipation of LIGO observations. ...
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4answers
185 views
2
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1answer
105 views

How does LIGO account for curvature of Earth?

Using an earth curvature calculator, I found that at a distance of 4 km (the length of LIGO's arms), more 1.26 m is hidden by the horizon. When constructing LIGO, did they account for the curvature of ...
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1answer
12 views

Simulating open water acoustics in a tube

For the purpose of testing an underwater acoustic transmission it is possible to use a tube filled with water with a transducer at one end and a hydrophone at the other. The problem is that sound will ...
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1answer
32 views

How to prove this material derivative formula rigoriously with experiment or prove it without the chain rule? [on hold]

How to prove this rigoriously by experiment or prove it with other mechanics law but without the chain rule? This is coming from reddy's introduction to continuum mechanics. Also please explain ...
0
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1answer
33 views

Could the universe really be expanding at a constant rate? [on hold]

I was just thinking, sorry if this idea is idiotic, but since we know galaxies move away from each other at an accelerating rate, could this be due to a weakening gravitational force between galaxies? ...
0
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1answer
84 views

What is the proof of gravity being curvature of spacetime?

According to general relativity gravity is an illusion caused by curvature of space-time, rather than real force. As I understand there is overwhelming experimental evidence to support general ...
2
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0answers
19 views

How do large interferometers work?

In very large Michelson interferometer a such as LIGO, how can we keep the two light paths at the exact same distance in order to avoid any unwanted and noisy fringes shift? When I used to make ...
20
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3answers
2k views

How strong were the gravitational waves that LIGO detected at the source?

The articles I've read say that the distortion we see here is much smaller than a proton. What about at the source? Would these waves have been strong enough to see macroscopic effects near the binary ...
106
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7answers
8k views

Why is the detection of gravitational waves so significant?

LIGO has announced the detection of gravitational waves on 11 Feb, 2016. I was wondering why the detection of gravitational waves was so significant? I know it is another confirmation of general ...
4
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4answers
117 views

How do they find the energy of a photon?

Is the actual energy of a photon ever measured? How is it done? I read that a photon is usually identified by diffraction, that means its wavelength is measured, is that right? In this way we ...
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1answer
24 views

Wave optics physics

When does monochromatic beam of light incident on a reflective surface get completely transmitted.according to the question what exactly the word transmitted means? I'm little bit confused .could you ...
0
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1answer
21 views

What do I need to calculate UV intensity?

I have a mineralogical UV lamp that I want to use for some research, I only know it's wavelengths. To calculate the µJ/cm3, what else is needed? Distance, time, wattage? Is the value I'm looking for, ...
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0answers
19 views

photometric redshifts - the origin of 1 / (1+ zspec) in photometric accuracy

i have a training sample of sources with known spectroscopic redshifts ($z_{\rm spec}$) and i run a photometric fitting code that uses a template to determine the photometric redshifts ($z_{\rm ...
6
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2answers
712 views

Evidence for quantum gravity from gravitational waves

The rumor spreads that physicists will make their big gravitational wave announcement this thursday. I am far from being an experimentalist, but I want to know if there is any chance that the ...
1
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1answer
32 views

Open Source Particle Tracing Software

I am fairly new to this forum. I am designing an ionospheric plasma testing environment in a thermal vacuum chamber and to do so I require some form of multi-physics package for simulations .. such as ...
2
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2answers
34 views

Why did James Chadwick use berryllium to discover neutrons?

In Rutherford's alpha particle scattering experiment he used gold foil because it's malleable and can be drawn into very thin sheet. Why did James Chadwick use Berryllium while discovering neutrons ...
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0answers
21 views

How to arrange a 3d cymatics experiment?

Various researchers have filmed levitating polystyrene using sound waves. If i were to take 3 speakers and attempt to visualize the standing wave fields formed by the three speakers, how would i do ...
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1answer
35 views

Single slit diffraction - choosing a wavelength?

For the classic experiment of determining the slit width of a single slit. If we assume the rough order of magnitude of the width is known. What factors determine the choice of wavelength? (Clearly ...
0
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2answers
54 views

Is the video “How to Reveal Subatomic Particles at Home”'s explanation of its experiment misleading?

https://www.youtube.com/watch?v=wN_DMMQEhfQ The video asserts that along the path of an electron or muon, a trail of condensation will appear. But from what I understand, if an electron or muon (both ...
2
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0answers
33 views

How to control a dc motor? [closed]

I am in 8th standard and I am doing a project on 3d printing pens. I want to know how to control a dc motor, so that when I press a button it should increase its speed gradually till it reaches its ...
35
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2answers
3k views

Cause for spikes in trinity bomb test

In Richard Rhodes' book, The Making of the Atomic Bomb, I was reading about the Trinity nuclear test. High speed photos were taken and this one is from <1ms after the detonation. The book mentions ...
2
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1answer
45 views

publication ethics [closed]

What does it mean if somebody publishes the same concept of my paper with some changes without citing it although the paper has been published 5 years before his, and the concept was clearly first ...
0
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0answers
87 views

Gravitational waves: novel or confirmatory? [duplicate]

If the rumors are true and gravitational waves have been detected, would we learn any new fundamental physics from them? Or is this simply an important confirmation of a prediction of general ...
0
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0answers
15 views

Using thin needle for object and thick needle for image

I have performed an experiment to determine the focal length of a concave mirror in my school lab. It consists of an optical bench with two needles, one as object and one image. We basically try to ...
6
votes
1answer
83 views

Why is an airplane propeller so different from a boat propeller in shape? [closed]

Examples: Airplane propeller Source:http://www.sensenich.com Boat propeller Source:http://www.nauticexpo.com It is obvious that the airplane propeller is drastically different from the boat ...
6
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0answers
44 views

Experimental Hopf fibrations

Recently I read a paper where the authors experimentally constructed a Hopf fibration - that is, they created a quantum system where the nematic vector field of the system had a non-zero Hopf ...
0
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1answer
43 views

Why does quantum mechanics produce different predictions for Bell test experiments than classical mechanics?

I understand that experimental results from Bell test experiments have shown that measured correlation is a cosine function of the angle between the detectors. What I am struggling to grasp is why ...
1
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3answers
131 views

Is it correct to calculate the propagation of error in this way? [closed]

I conducted an experiment and measured the values of $R$ and $H$ to calculate $v_i$. The equation used is: $$v_i=\sqrt{{gR^2}\over{2H}}$$. My average values ($v_i$ is calculated only for the average ...
0
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0answers
34 views

Can 1km diameter ball of water preserve it's integrity before hitting the ground falling from 10km altitude?

I still argue with my friend over some big ball of water (1km in diameter) that is being instantly created 10km over the surface of the earth in perfect sphere form. I stated, that as it hit the Earth ...
1
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1answer
41 views

Will an Electrical Engineering Minor give me a significant advantage in experimental physics? [closed]

I'm currently choosing courses to complete in my university degree (science) and thought completing some basic electrical engineering may be useful if I go into academic experimental physics research. ...
0
votes
1answer
35 views

Wind resistance [closed]

You have a metal plate/sign (max weight $5\, \text{kg}$) $1200\, \text{mm}$ long and $400\, \text{mm}$ high pivot/hinge at its base. A windspeed of $90 - 100\, \text{km/h}$ is applied to one face of ...
0
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0answers
55 views

How to measure size of small particles of $mm$ level? [on hold]

Is there any way to measure dimension of small particles (mm sized) such as rice grains accurately? I know there are techniques such as laser or x-ray diffraction, but the equipment needed are too ...
6
votes
1answer
54 views

Is there a tool to measure the chemical potential of a system?

Let's suppose I put you inside a room filled with a gas. You can measure its pressure directly with a barometer. You can measure its temperature directly with a thermometer. Can you measure its ...
4
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0answers
66 views

How can one confirm creation of magnetic graphene?

Recently my high school physics teacher contacted me looking for an expert to ask about this situation. I am paraphrasing his correspondence below: I just had a a student accidentally create ...
0
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0answers
34 views

Obtaining an angular distribution from the Klein-Nishina formula

I'm having trouble on how one might obtain an angular distribution from the Klein-Nishina formula for compton scattering of polarised photons, more specifically on how this report is obtaining it. ...
0
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0answers
7 views

Circularly Magnetized Neodymium Torus With Minimum Flux Leakage

I'd like to conduct some experiments related to Aharonov-Bohm. In particular, I'd like to investigate the irrotational vector potential gradient. A simple geometry for this is the major axis of a ...
0
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0answers
13 views

magnetic field due to current carrying coils

In the Helmholtz configuration, why is the magnetic field between the two coils uniform (I know the mathematical expression)? Can anyone please explain this physically? When the distance between the ...
1
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0answers
67 views

How would you build a small cyclotron (particle accelerator)? [closed]

I heard Michio Kaku built a small cyclotron when he was young. I bought a book called "Principles of charged particle acceleration" where it explains the basic functioning of particle accelerators. ...
0
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2answers
20 views

i have a thin film deposited on a glass substrate, when i measure trasmittance for it ,should i use a reference glass or air? and why

i have a thin film deposited on a glass substrate, when i measure trasmittance (T) for it ,should i use a reference glass or air? and why regarding these points: for bare glass T=88 % for thin film ...
3
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1answer
102 views

Is it experimentally proven that photons travel at speed $c$ in vacuum?

Are there experiments which show that single photons (not classical em waves) travel exactly at $c$ in vacuum? What is the error bar in that case? The question is posed due to the fact that loop ...
1
vote
1answer
42 views

Experiment: releasing the copper bar above a permanent magnet

A classic experiment shows that when we drop a magnet through a copper coil long tube, there is eddy current induced in the coil. Then, due to lenz law, the motion of the magnet will be opposed and it ...
1
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0answers
20 views

Coupling into FC/APC fiber

I am currently attempting to couple a 405nm laser diode into FC/APC fibre. The fibre is mounted on a flexure stage approximately 15.3mm from an f=15.29mm lens. I have managed to couple into the core ...
5
votes
1answer
49 views

Will the speed of the wind produced by a fan increase continously to infinity with the propeller spin speed?

Imagine a scenario: On a stand, an $RC$ plane motor is mounted on a stand. The motor has a $8x4$ prop attached to it. In the theoretical model, if the spin of the motor can be increased infinitely ...