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

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1answer
19 views

Ideal gas law in open volumes

I often find in text books that the ideal gas law given by $p\cdot V=m\cdot R\cdot T$ is applicable in a closed system, still, some use it for open systems (like freezing the system at a given ...
2
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1answer
47 views

Are there any experimental tests of non-locality / Bell inequalities that do not rely on spin?

All the experiments I know, which have been performed to test Bell inequalities, are somehow based on measuring the spin degree-of-freedom of some particle (usually photons, sometimes electrons). I ...
1
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1answer
36 views

What will be the effect of placing a light source very close to a photodiode?

What will be the effect of placing a photodiode really close to a laser source and what should be the appropriate distance between a light source and photodiode to get maximum output current?
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1answer
78 views

Why Are Normal Shock Waves Unstable in a Converging Channel?

While learning about shock waves in an introductory Gas Dynamics course, it was revealed that normal shocks are unstable if formed in a converging channel. Even if the local conditions ostensibly ...
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0answers
90 views

Forward's frame-dragging accelerator

On 1962, Robert Forward studied the possibility of using General Relativity Frame-Dragging effects to accelerate probes inertially (that is, without feeling any internal G-forces) One of the ideas is ...
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1answer
69 views

Circuit breaker Trips during thunderstorm

The circuit breaker at the electrical mains trips at home when there is a thunderstorm outside. Why does this occur?
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0answers
29 views

Experimentally diminishing random errors for low wavelength UV observations

Part of the work that I do involves observations of solar low wavelength UV observations, specifically UV-B and UV-A II (up to 340nm). I have noticed that when I observe responses on a CCD or CMOS ...
1
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1answer
26 views

Diffraction and Shape in the grating

Suppose, I use a laser with a known wavelength of 650 nm through a "opaque grating" that has a pattern of holes of same shape and size. We can see the pattern on the screen. We know the distance ...
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0answers
14 views

How big can be gradient of magnetic induction (in lab)

I'm thinking about magnetic levitation and how big force can push a diamagnetic when we put it in inhomogenious magnetic field. As far as I know, force exerted on a diamagnetic is proportionald to ...
1
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1answer
33 views

Cold welding of a metallic surface

I have heard of cold welding, it's said that it's only possible if the surface is very clean. Can cold welding be accomplished by shearing a metal object and then immediately touching the newly ...
0
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1answer
379 views

Difference between Vernier constant and least count

What is the difference between the Vernier constant and least count of a Vernier caliper?
1
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1answer
38 views

Expansion of the universe [on hold]

If matter cannot be created nor destroyed, I would assume that the universe expands only to the point that energy is expressed from the objects inside it until it collapses onto itself, given as the ...
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2answers
476 views

Why is there a hiss sound when water falls on a hot surface?

Why is there a hiss sound when water falls on a hot surface? I have searched a lot, asked my teachers but none of them seem to give me the logical answer to it.
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4answers
75 views

Will 5 pizzas in the same Hot Bag stay warmer than 5 pizzas in 5 separate Hot Bags?

For example, say I am delivering 5 pepperoni pizzas to 5 different addresses. In one scenario, I Keep all 5 in the same insulated Hot Bag, I carry that bag to the door, and I quickly remove one of the ...
2
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0answers
31 views

What is the highest frequency directly detected?

The Feynman Lectures of Physics states: In fact, although we mentioned many frequencies, no phenomenon directly involving a frequency has yet been detected above approximately $10^{12}$ cycles per ...
2
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0answers
15 views

Why is the current measured through a thin film increasing with time? (experimental question)

I'm doing an experiment: I'm thermally evaporating a metal in a vacuum onto a quartz (very insulating) substrate, between two gold contacts that I use to measure the current through the (growing) ...
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0answers
12 views

If a nozzle that converges from an inside diameter of 5cm to 3.5cm carries a gas at a VFR of 0.10 m^3/s, what is the change in average velocity? [closed]

If a circular nozzle that converges from an inside diameter of 5 cm to 3.5 cm carries a gas at a volume flow rate of $0.10 m^3/s$, what is the change in average velocity of the gas? (A nozzle being a ...
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2answers
91 views

Experiment which shows that Newtons third law is not true for magnetic forces

I am just reading David Morins "Introduction to Classical Mechanics". He writes about Newtons third law the following: It holds for forces of the “pushing” and “pulling” type, but it fails for ...
2
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1answer
26 views

Thermal emission cathode electron velocity distribution

I can't find any experimental data (or theoretical expression) on what is the velocity (or energy) distribution of thermal emission cathode electrons emmited from the cathode at approximately 2000 K ...
2
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1answer
74 views

References on experimental realization of quantum one-dimensional infinite-well model

Can someone point me to the examples, or references, of experimental realization of the quantum one-dimensional infinite-well model? [EDIT] The motivation of this question is the curiosity - though ...
0
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1answer
107 views

Beryllium Vacuum Sphere Boat/Aircraft

Is it possible to make a solid rigid evacuated "balloon" out of Beryllium or other elements or alloys? The critical buckling pressure at which an evacuated sphere is given as $$ ...
6
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2answers
252 views

Why propagation of uncertainty is linear?

I'm in doubt with one thing: let's imagine that we have $n+1$ quantities, $n$ of them being directly measured, and the other one being related to the first $n$ by a function $f : \mathbb{R}^n \to ...
1
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1answer
198 views

Questions about MTW's “thousand” tests of the Einstein principle

In Misner, Thorne, Wheeler (henceforth written as "MTW"), "Gravitation", Box 16.4, there's an experimental setup construction (or method) presented by which "Each geodesic clock is constructed and ...
6
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2answers
434 views

What experiments compete with BICEP 2, and when are their results expected?

The recent results of the BICEP 2 experiment published on March 17th 2014, has generated a lot of media attention, with the general consensus being that "this is a major discovery" perhaps leading to ...
1
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1answer
12 views

The strength and control over the strength of electromagnets, correlation between the strength and weight of the magnets

I am currently working on a project that aims to use the attraction & repulsion between two electromagnets as an alternative to weights, from a physiotherapy and rehabilitation perspective to help ...
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0answers
15 views

Ellipsometry measurments

Why it is good to measure on a wavelength range in ellipsometry instead of using a single wavelength. I understand this that the measured data (ψ and ∆ ) plotted against wavelength and if we have ...
3
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4answers
109 views

How are theories in physics validated against existing knowledge in practice?

Often you hear people mention how most attempts at Unified Theories haven't "accounted for all the experimental observations". The question is, how do you know you have accounted for all of the ...
2
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2answers
91 views

what could generate a high-pitched whine in electronics where the frequency depends on the current?

So I was operating a Laue machine recently which generates x-rays and fires them at a sample, and I noticed that there was a high-pitched whine coming from the instrument (nothing abnormal, just ...
28
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4answers
4k views

Has gravity ever been experimentally measured between two atoms?

Has there been any experiments, or are there any references, demonstrating gravity between atoms? If so, what are the key experiments/papers? Or if not, what is the smallest thing that has actually ...
0
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0answers
18 views

Strength of Magnet in Magnetic Bearings

While reading about magnetic bearings, one reads about passive/active magnetic bearings. By passive, one means no electric current is put into the bearing for attaining magnetic levitation/flux. In ...
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4answers
204 views

Detecting absolute motion inside a box

This is not a contradiction and I know it is impossible but still consider a thought experiment by me and point out if something is wrong. See the following picture and then the explanation follows. ...
3
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1answer
72 views

What is making these subatomic honeycomb shapes and gaps in this graphene image?

I just read yet another graphene discovery and saw this STM image: Nice photo, it begs two questions: What is that secondary honeycomb structure, the one about 20x smaller than the atoms ...
1
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1answer
75 views

Upper limit to electric charge confinement?

The following questions are not intended for conventional capacitors (which stores excess charge on the outside surface), rather a type of hypothetical capacitor which is designed to confine charge by ...
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2answers
68 views

Reference frequency

In my experiment, I have to obtain a relation between magnetic field of a solenoid and the applied Vp-p. The setup is as follows. http://www.teachspin.com/instruments/faraday/ Does my choice of ...
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0answers
34 views

Looking for binning software [closed]

I'm looking for a software which should do the following Take a set of data $X$ and $Y$: Procedure A Finds the max and min in $X$ Divide this interval in a number of bins chosen by me For each bin ...
0
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2answers
23 views

Weight of solid partially immersed in water

Suppose an object(spherical) is kept in water and 9/10 of the object is inside the water 1/10 floats. Find the weight of solid inside liquid. By Archimedes principle, if an object is immersed in a ...
40
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6answers
7k views

What technology can result from such expensive experiment as undertaken in CERN?

I wonder what technology can be obtained from such very expensive experiments/institutes as e.g. undertaken in CERN? I understand that e.g. the discovery of the Higgs Boson confirms our understanding ...
6
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2answers
2k views

What is the most counter-intuitive result in physics? [closed]

I think that relativity and quantum mechanics would provide some good examples.
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2answers
212 views

Has magnetism been experimentally demonstrated at the quantum level?

I've learned that magnetic fields are generated by electric currents, and that electric current is the motion of electrons and stuff like that. Many textbooks also talk about "point charges" and have ...
1
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1answer
48 views

Error calculation for experimental data

I have the list of experimental values: $$\{w_i \pm \Delta w_i\},$$ where $w_j$ is a mean value and $\Delta w_i$ is an error. I want to calculate the second list $\{a_i \pm \Delta a_i\}$ according to ...
1
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1answer
28 views

What is the easiest way to demonstrate low magnetic flux NMR on the bench?

I'm trying to build my own low fux density bench NMR set-up, and am well-versed in electronics. Continuous Wave is supposed to be the easiest. I see commercial instruments that stimulate elements in ...
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1answer
124 views

About the Large Hadron Collider [closed]

I think Physics is fascinating , especially those really clever experiments one can do that demonstrate some important principle and probably don't cost a lot of money to make. Also the Thought ...
28
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6answers
2k views

How to determine your position underground?

Crossed my mind after random rant on wikipedia that lead me to articles about chronometers and measuring position. Let's assume I were trapped in the underground laboratory with lots of equipment ...
2
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2answers
65 views

Where can I find the datasets from LHC?

I know that most of the datasets from ATLAS or other particle physics experiments are terabytes, but I was just curious is there any place where one can find them to download? And one more question, ...
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0answers
49 views

Flow from the bottle

I made some calculations about flow from the bottle, but problems occured when the experimental data came back. Need to refine calculations, but problems occur when trying to link the angle to the ...
3
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2answers
137 views

What's wrong with this experiment showing that either FTL communication is possible or complementarity doesn't hold?

The assumptions are: Alice and Bob have perfectly synchronized clocks Alice and Bob have successfully exchanged a pair of entangled photons The idea is simply to have Alice and Bob perform the ...
3
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1answer
119 views

Is this the correct way to I combine multiple interdependant pressure readings?

I want to measure the density in different layers of a suspension. To do this I want to place pressure sensors at different heights. Let's assume that the sensors are not by orders of magnitude more ...
3
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1answer
99 views

Motion in a Paul trap: $2n$th harmonic with larger amplitude than $n$th harmonic

Using a Paul trap, we captured the motion of a light charged particle (based on a rotating potential applied by AC current). Our rotational frequency was 50 Hz, and so when used FFT on the data, we ...
1
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1answer
44 views

Data/signal from a black hole to observe a singularity

I wonder if a situation is possible where, we measure some signal/property concerning a black hole. Supposing the measurement we make with some telescope, gets us the Fourier transform coefficients of ...
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2answers
2k views

What exactly do we see on the famous neutrino image of the sun?

An answer to the question If we could build a neutrino telescope, what would we see? contains a link to a neutrino image of the sun by the Super-Kamiokande neutrino detector. There it says that ...