# Tag Info

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How do we measure the position of an electron with a light source? Experiments with elementary particles are mostly scattering experiments. One needs the source of the particles and a detector that can identify particles. In this figure we see electrons one by one passing the slits and leaving a point (x,y) on a screen sensitive to electrons (deposition ...

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As we moved from Geo-centric and Helios-centric models of the universe, natural philosophers began the trend of viewing the universe as 'less anthropic'. That is to say, our existence and perception do not impose significant 'weight' or 'influence' upon the casual billiards of heavenly bodies. The evolution of the cosmos occurs irrespective of the presence ...

0

When light passes through a diffraction grating, it gets diffracted at many different angles. Something like this image happens. The smallest diffraction angles correspond to $m=1$, the next angle corresponds to $m=2$, etc. I'd imagine in your lab you measured the FIRST spectrum line, so that means $m=1$. As a side note, $m=1$ corresponds to a phase ...

1

Soft x-ray optics typically uses grazing reflections on suitable mirror materials and gratings (e.g. Pt coated optics) or crystals and the detection can be done with scintillators using CCDs or PMTs. Commercially available instruments have approx. 0.2eV resolution (2000 lines) while research grade instruments can achieve much higher resolutions e.g. 30000 ...

1

It is possible to measure wavelengths of light to many decimal places. When you see accurate determinations of atomic energy levels, they were done spectroscopically, looking at absorption or, more commonly, atomic fluorescence. Since $E=hc/\lambda$, one can accurately convert between wavelength and energy. When excited, atoms emit many wavelengths of ...

0

In electronics , a voltage divider (also known as a potential divider) is a passive linear circuit that produces an output voltage ( V_out ) that is a fraction of its input voltage ( V_in). Voltage division is the result of distributing the input voltage among the components of the divider.Consider a point A on a rheostat,or simply take a potentiometer.Now ...

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A 2 piece fiberglass pool filter is plenty large and can withstand the pressure. A stainless steel belt goes around the sections after you put the RUT in there. Add a hose and use a bicycle pump if you cant achieve 40 foot hose head. It is only 18 psi.

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As several people have advocated using pressure vessels, I'll add my own take on this. Pressure vessel safety Compressed air in an uncertified vessel can be extremely dangerous. You need a pressure of about 1.2atm gauge to simulate 40ft of water. That's about 2.2atm absolute. I'm not going to perform an integration here, but air at these pressures is ...

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I was going to suggest building a centrifuge. I am guessing you don't need to attach cables to your robot. And yes, a centrifuge can be dangerous. But Paul has less complicated solutions.

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Fit a valve onto the body of your submarine, and use a vacuum pump to pump out all the air. 1 atmosphere is equivalent to 10.3 meters (33.8ft) of water. Then you only need 6-7 feet of water to reach the pressure difference you want to test.

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Find a rigid 40ft-long water hose, attach it to your tank vertically and fill it with water.

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I think John Rennie's is a bit misleading. You don't actually need 12 tons of weight. You can get the same 18 psi from a 40 feet garden hose hung vertically. Attach it to the lid of a pressure cooker, and you'll have a "pool" that's 40 feet deep. The pool doesn't need to have the same diameter throughout. The two challenges are (1) attaching the garden hose ...

3

As far as I know the 33 cm difference is the current champ for the measurement. The stability of part(s) in $10^{18}$ is only achieved after running for a certain length of time, and averaging out white frequency noise. Their actual result was obtained over a period of time (40,000s and 100,000s for the high and low measurements) and was 37 ± 15cm. They ...

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How much space do you need, and what shape does it need to be in? If it's a stationary bot, call an excavating company and ask them for a quote on drilling a 24 inch hole 40 feet deep. They will bring a humongous machine out to your place, punch a rather large hole in the ground, and be gone before lunchtime. Visit a home center for some 6mil plastic rolls, ...

4

Fill the cavities of your vehicle with an environmentally friendly liquid like glycerin. This will take care of a possible water leak, at least to the extent necessary to survive for a short amount of time in a low pressure environment. Before you do that you have to ask the event organizer if that is an allowed design strategy (what "big oil" can do is not ...

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It's easy to work out what weight you need, because it's the weight of 40 feet of water. The pressure at a depth of 40 feet is simply due to the weight of the 40 feet of water above. Let's work in SI units, so 40 feet is 12.2 metres. Suppose the top of your tank has an area of one square metre, then the amount of water above it would be 12.2 cubic metres ...

0

Interesting question. Mathematically the apparatus using the Vl (velocity of light) and Ve (velocity of the aether) can not prove anything except Vl+Ve (1st leg) Vl (2nd leg) + Vl (3rd leg) +Vl-Ve (4th leg) = 4Vl which really demonstrates nothing. it will only show a difference in the fringes when accelerated. the apparatus can not get past the Doppler ...

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I'm afraid you're overcomplicating things, aepryus. Yes, most modern clocks use electromagnetic phenomena, but your pendulum clock employs gravity in much the same fashion as your water-drop clock. The clock rate doesn't depend on gravitational potential, it depends on the first derivative of potential, the "slope" as it were. The force of gravity. And this ...

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I don't believe there are any plausible experiments which have proved the theory of relativity and I do not believe that time can pass slower on one body than it can on another. Imagine a train moving at 100km per hour relative to someone standing by the train tracks. A person on the train turns on a torch. The torch is on the train and would have the same ...

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Assuming the question is about creating superpositions of eigenstates of the atomic Hamiltonian, one can do this by shining coherent electromagnetic radiation at the frequency $\omega$, such that $E = \hbar \omega$ is the energy difference between the two atomic states. This causes Rabi oscillations, so that the quantum state oscillates between the ground ...

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Measuring T-line power flow from the ground without contact is tricky, especially near the tower. The tower is a solidly grounded structure and tends to sink the EM fields to ground, and the conductors are far from your position (high in the air). Better to move to mid-span where there is no tower and the conductors are closer to the ground. Also better to ...

2

Stokes Law is not going to apply in this situation because the water flow around the ball will be turbulent not laminar. The way to see this is to calculate the Reynold's number. For a sphere this is approximately given by: $$Re \approx \frac{\rho_wdv}{\mu}$$ If we feed in $\rho_w = 1000$ kg/m$^3$, $d = 0.00317$ m, $v = 37$ m/s and $\mu = 0.001$ Pa.s ...

1

You seem to be onto something. This research paper on arxiv suggests a linear relation between the hall coefficient and temperature for a certain strongly disordered metal; the analysis probably does not apply in your case with copper, but was included because it is interesting, is current research and deals with the relation between the hall coefficient and ...

3

It means that when the neutrinos hit electrons, the electrons are moving preferentially in the same directions that the neutrinos were moving. So when we are building a water Cherenkov detector for solar neutrinos, the Cherenkov signal will be coming from the direction of the sun. This is very advantageous to suppress background and because of the daily and ...

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When you say "improves the reliability", well that is not clear at all, because you have reduced your sample size and possibly introduced an (unknown) bias. Median filtering is typically used where you do not fully understand the noise properties of your sample and where there may be cases of results that are way out from the expected result because of rare ...

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According to an Intel study, soft-error failure rate at 16 nm is expected to be more than 100 times that at 180 nm, because with scaling of operating voltage, the critical charge required to ﬂip a stored value has been decreasing. Also, in atmospheric radiation, particles of lower energy occur far more frequently than those of higher energy and hence, with ...

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In superfluid helium-4, the phonon excitation spectrum includes a mode which has the same energy and momentum as a neutron with a speed of about 440 m/s (wavelength $\lambda \approx 9\,Å$). You can create a neutron beam which contains only 9 Å neutrons by starting with cold neutrons and being clever with diffraction from crystals. If you send these ...

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I use this arrangement in my introductory classes when time allows, but not for momentum. I call it the "work-energy mini-lab". (It's a mini-lab because I don't expect a detailed write-up and guide the class through some of the harder analysis.) Some things to note. By measuring how far the mass hanger has to drop you get the distance over which the ...

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You need to keep the amount of time the same as well. The change in momentum of a system is equal to impulse delivered to it, which is just the time-integral of the force: $$\Delta \vec{p} = \vec{J} = \int_{t_1}^{t_2} \vec{F} \, dt = \vec{F} \Delta t \text{ (if \vec{F} is constant with respect to t.)}$$ So just having $\vec{F}$ constant isn't enough; ...

2

I don't know nearly enough QFT to address the background or implications of your question. However, I'd basically answer yes to your first two questions, but it depends a little on your definition. A single phonon mode is not localized in space. However a wave packet can in principle be built up of a small range of frequencies, giving a fairly well defined ...

0

I could be wrong, but I remember reading that scanning tunneling microscopy can be used to measure $|\psi|^2$. A quick Google search brought me to this paper, "http://www.ncbi.nlm.nih.gov/pubmed/19090685." I'm sure you can find more information by looking into STM online.

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The wave function is connected to an experimentally observable value through its complex conjugate square, which gives the probability of an interaction or a decay happening; from this a crossection for the interaction can be predicted, number of events versus some variable in appropriate units. Example: the experiment can measure very many decays of the ...

1

Experimental physicists are very visual people. They are more interested in seeing the wavefunction. Calculating it is the work of a theoretical physicist. "Catching sight of the elusive wavefunction", would be a good read for you at this point. As you proceed with Griffiths, you will see that in experiments we measure certain quantities, called the ...

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In the 2 glasses there are 4 surfaces, i.e interface air/glass, and 8 surface orientations (a..h) and plenty room for interference between reflections and the main beam. LASER (air) a1b (glass) c2d (air) e3f (glass) g4h At each interface the is reflection that will be reflected forward again (self-interference) look for iridiscence in ...

1

At a guess, the effect rises from the fact that your interferometer is not properly aligned. The presence of linear, rather than circular, fringes suggests that there is an angular misalignment. Then moving the wedge causes a lateral shift in the intersection point of the beam and the angled slide, which results in a shift in the apparent position of the ...

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This answer is based on Floris' insight that the slides might be bent. Let's say the laser hits the slide at an angle of $\theta$ and travels through the panel at an angle of $\theta'=\sin^{-1}({n_a\over n_s}\sin(\theta))$. Let's assume the curvature is light enough that the laser essentially exits parallel to how it entered. I am also going to assume you ...

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If we calculate the schwarzschild radius (and below is a really convenient link if you don't want to calculate yourself. http://physics.unl.edu/~klee/flash_astro/bhole_sim010.swf And if we look at the size of an atomic nucleus: 1.6 fm (1fm= $10^{−15}$ m=0.000000000000001 m) for a proton in light hydrogen to about 15 fm for the heaviest atoms, such as ...

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It is worth stressing that black holes are predictions of classical General Relativity models. Our experimental data have established that the underlying level of nature is quantum mechanical. There is a large body of research on quantizing gravity and unifying the three forces studied with particle physics experiments with the gravitational force. String ...

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The smallest possible black hole that could be observed would be one with a mass on the scale of the Planck mass (~ 22 µg) and a radius on the scale of the Planck length (really small). Thermodynamics makes it impractical to pack multiple particles into such a small space, so the best bet would be to accelerate elementary particles to have relativistic mass ...

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This is speculating - but if your slides are of non-uniform thickness, or they are bent as a result of the pinching, they will present a different path length in one leg of the interferometer (and therefore give rise to a shift in the fringe pattern). This may become clear by looking at this diagram: In the diagram on the left, the total path length is ...

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In 2008 Ulf Leonhardt of University of St. Andrews UK led the first research group to make an artificial black hole. Its purpose was to look for experimental evidence of "Hawking Radition," photons and neutrinos emitted by black holes. "Hawking Radiation" couldn't be detected from astrophysical black holes because the signal would be overwhelmed by the CMB ...

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Fill a garden hose with water. Hold both ends closed, and walk to the "higher" pond. Have someone helping you hold the end of the hose under water. Now walk to the other pond (still holding the end of the hose shut). Hold the hose near the surface of the pond - you should feel water pressing against your finger. Make a very small opening and observe the ...

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are the decay products produced totally probabilistic or can we "tune" an accelerator to increase the probability of a particular decay channel occuring? Once a particle is produced, it decays completely independently of its production. The only dependence on production occurs when, for instance, a particle is produced in an entangled state and ...

0

Heat flows into a cooler condition; cold does not flow into a warmer condition. The 'rate' of cooling is dependent upon the difference between the coffee and the surrounding, ambient temperature. That is, a very hot cup of coffee will cool "faster" than a just warm cup of coffee. As the very hot cup of coffee starts to approach room temperature the rate of ...

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Components: Muon Spectrometer: (1) Monitored Drift Tube (2) Thin Gap Chamber Magnet system: (3) End-Cap Toroid Magnet (4) Barrel Toroid Magnet Inner Detector: (5) Transition Radiation Tracker (6) Semi-Conductor Tracker (7) Pixel Detector Calorimeters: (8) Electromagnetic Calorimeter (9) Hadronic Calorimeter The ...

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Are vacuum fluctuations more probable near a charge, for example an electron with negative charge? I'm going to say no, because renormalization is more to do the virtual particles of QED rather than vacuum fluctuations. As for virtual particles, see Matt Strassler's article and note this: "The best way to approach this concept, I believe, is to forget you ...

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