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

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17 views

Spectral Response of a photo-resistor (CdS) and phototransistor (Si)!

I am doing a report on an experiment I took and I have completed every section apart from this last bit. I am told to compare the spectral response of a CdS and Si. I am unable to construct a graph ...
3
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2answers
232 views

Evidence that nuclei contain neutrons and protons (other than nucleons appearing if a nucleus is smashed)?

This may seem like a silly question, but I believe this to be very fundamental because the Standard Model of particle physics seems based on the axiom or assumption that neutrons and protons exist ...
3
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2answers
105 views

Water Waves in the Wake of a Boat

As a boy I noticed that the waves from the wake of my model boat would fan out. If I looked at the end furthest from the boat the front had turned so that it was almost running in the same direction ...
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1answer
34 views

How is the the lower-limit of the proton lifetime measured experimentally?

Wikipedia says : Recent experiments at the Super-Kamiokande water Cherenkov radiation detector in Japan gave lower limits for proton half-life, at 90% confidence level, of 6.6×10^33 years via ...
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3answers
87 views

Has anyone tried Michaelson-Morley in an accelerated frame?

After doing much more digging than I thought I had to do, I found out that the speed of light is NOT invariant in an accelerated reference frame. Has anyone done any experiments to confirm this? In ...
3
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3answers
356 views

What would happen to me if I was in the LHC while it was running? [duplicate]

This is possibly a stupid question, but one I have been always wondering. What would happen to me if I was in the center of the Large hadron Collider while it was running? Would the energy of the beam ...
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0answers
21 views

What is the spin of a magnetic impurity?

I am reading this seemingly important paper Local Magnetic Moment Associated with an Iron Atom Dissolved in Various Transition Metal Alloys. It is strange to me that the magnetic impurity has ...
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3answers
54 views

Double slit experiment

What's the simplest way to describe and show the double slit experiment? I have to perform an experiment proving how it all works in my physics class.
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2answers
28 views

Optimizing surface geometry for thermal radiation

I'm working on vacuum technology for a scientific project and one of the challenges is to optimize the cooling of 2500°C metals in vacuum. I'm wondering if it would be useful to design a grating on ...
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2answers
33 views

wormhole time machine and violation of uncertainty? [duplicate]

Let's asssume we have a wormhole that allows sending info to the past and receiving information from the future. Next, we have a particle moving in two dimensions, for which we can evaluate $ p_{y} $ ...
2
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1answer
21 views

What is the difference between a measurement and an experiment?

For example, say I want to determine the atomic structure of a bio molecule. I purify the molecule, get it to crystallize (probably though trial and error), shoot it with X-rays, observe the scatter ...
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4answers
4k views

Can water falling from a tap follow a spiral path?

The faucet design depicted below is driving me crazy. The water falling from the tap appears to follow a spiral path. No one seems to agree whether it is physically possible for the water to spin in ...
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3answers
67 views

Mathematical formula for hysteresis [closed]

For my final year project, I need to design a lab to generate a hysteresis loop. But I have no idea how to do it. Is there any mathematical function or any code or any article which would help me to ...
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0answers
22 views

ZnO nanorods synthesis

Could someone please let me know the steps to be used for sol-gel method synthesis of ZnO nanorod arrays using PVA as solvent and Zn acetate as precursor? I need vertical and uniformly aligned NR ...
2
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0answers
60 views

How do we get the power spectrum through the CMB?

How do we get the power spectrum through observing the CMB?
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5answers
321 views

Where does General Relativity (GR) fail experimentally? Experimental shortcomings of GR?

When speaking with researchers and professors at my physics department, I sometime catch this undertone in the conversation when speaking about GR: almost as if some are not entirely convinced about ...
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1answer
54 views

Is the intuition of “absolute simultaneity” necessarily wrong?

I read about Einstein’s theories of relativity with all the interesting stuff like time dilation, mass increase and whatnot. And also about the relativity or conventionality of simultaneity. The ...
11
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2answers
403 views

Sun spectroscopy - Home experiment

We let the sun light run through a 5x3x3cm triangular glass prism and we examined the formed 'rainbow' in search of Fraunhofer lines. However, even though we looked close enough (even with a ...
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1answer
43 views

Light speed measured by observing Jupiter moons [duplicate]

The famous discovery that the light has speed measures the times of the immersion and emergence of Io, one of Jupiter's moons. However, I still can't comprehend this. Even when the Earth is further ...
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1answer
33 views

How are energy states of photons reason for frequency independence in Compton scattering

I am reading on Compton scattering, more specifically on how Compton interpreted his results. He observed that the frequency of the scattered radiation was independent of the material used, so he ...
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1answer
42 views

Experiment of plume of smoke

If a burning candle is covered by a transparent glass, the flame extinguishes and a steady upward stream of smoke is produced. Which factors will infulence the figure and properties of the plume of ...
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2answers
49 views

What kinds of behavioural anomalies can a zero-field-cooled (ZFC) / field-cooled (FC) split indicate?

If a material shows a spiltting in the ZFC and FC curves, is it necessarily superparamagnetic, or could there be any other reason for the irreversibility? I have heard spin glasses also show ZFC-FC ...
1
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1answer
13 views

Why friction is not taken to be varying jointly as roughness of the object along with normal force?

Frictional resistance to the relative motion of two solid objects is usually proportional to the force which presses the surfaces together as well as the roughness of the surfaces. But when we talk ...
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1answer
22 views

If two bodies move opposite to each other when brought in contact, what is the direction of force of friction?

We know that when a body is at rest and other is dragged over it then a force is produced which opposes the motion and consequently its direction is negative to the force applied on body to produce ...
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0answers
21 views

Such high mobility value for degrading structural properties

I have prepared Cu enriched ZnSe thin films with different concentrations of copper. The XRD and RAMAN results showed improvement in structural properties as the Cu content is increased up to 10%. ...
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0answers
34 views

Did Don Borghi's experiment show that neutrons can be synthesized purely from protons and electrons?

C. Borghi, C. Giori, and A. Dall'Olio published an article entitled "Experimental evidence of emission of neutrons from cold hydrogen plasma" appearing in Yad. Fiz. 56, 147-156 (July 1993) and Phys. ...
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1answer
32 views

Which g factor in an EPR spectra is the right one?

I was reading this introduction to EPR and it seems to imply both that there is a unique g-factor of a given compound, but also that we can calculate multiple g-factors for a compound. For example, ...
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1answer
43 views

How to derive time derivate of strain?

Data Time(s) Strain ----------------- 100 0.31 200 0.52 300 0.74 400 0.92 500 1.10 600 1.28 700 1.46 800 1.64 900 1.82 1000 2.00 I want to deduce ...
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3answers
59 views

How to find dielectric constants of ferroelectric materials experimentally?

What is the procedure to find out dielectric constant of barium titanate at different temperatures ?
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1answer
33 views

If any, what would be the ideal modulation frequency for a phase-sensitive light sensing experiment in a non-dark environment?

I have constructed some equipment for sensing a beam of light. The equipment is enclosed in a rudimentary darkbox to block out the majority of the ambient room lighting, but is still partially ...
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2answers
92 views

If a theory gets two predictions right, how likely it is that the rest of the predictions are true too? [closed]

The question lucidly defines what I am trying to inquire, so there is no need to elucidate it any further. Another question would be, General/Special Relativity has gotten some predictions right as ...
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2answers
127 views

How to demagnetize a magnet temporarily?

How to demagnetize a magnet temporarily? Is it possible making a permanent magnet demagnetize for a short span of time? Or at least long time but temporarily!
0
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0answers
24 views

Chemical composition and structure of Earth's inner layers?

How exactly do scientists determine the chemical composition and structure of Earth's inner layers, for example that the outercore is composed of liquid iron and nickel, and that the mantle is is ...
0
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1answer
44 views

Is there experimental evidence of time order inversion for spacelike events?

The title sums up the question. Given two events separated by a spacelike interval, say one takes place after the other in an inertial frame, then by a suitable boost we may invert the time order of ...
0
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1answer
37 views

X-ray pulse more powerful than national grid?

There is an article today in the BBC science section on the Linac Coherent Light Source, an X-ray laser in Palo Alto: http://www.bbc.com/news/science-environment-31483781. I don't trust the news with ...
3
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2answers
618 views

Why does ice become sticky the colder it gets? [duplicate]

I noticed that ice becomes stickier the colder it gets. I am reminded of the fool who stuck his tongue to a cold galvanized steel pole and got stuck to it. I am guessing that the pole was so cold that ...
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0answers
25 views

What is the limit of directly detecting a resonance?

Some resonances are extremely short-lived. With a lifetime of $10^{-23}$ seconds, they would travel just about the size of the proton ($10^{-15}$ m) even if they traveled at the speed of ...
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0answers
41 views

finetuned quantum experiments by Murch lab, do any have dynamics outside of basic QM formalism/ axioms?

a series of very finetuned quantum experiments have been reported by the Murch lab eg in 2 articles in Nature & analysis there,[1][2][3] some leading to dramatic accounts in the media.[4] do ...
5
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2answers
334 views

Evidence for electrodynamics in curved spacetime

Field theories in curved spacetime is usually formulated by integrating their Lagrangian over the curved spacetime. For example, for electrodynamics, we have the action $$ S = \int d^4x \left( ...
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0answers
19 views

Vortex-domain wall co-excitation

Both vortices (or disclinations) and domain walls are possible topological defects in a spin system with frustration, but I did't find reference about the interaction of these two. Do any stackers ...
5
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1answer
77 views

Options to correct rectangular laser beam profile?

We recently switched to a 405 nm laser diode which has a terrible beam profile -- it is a well-defined rectangle with an aspect ratio of about 10:1. The image below shows the collimated beam which ...
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0answers
23 views

Data Collection of oscillatory motion

I'd like to study nonlinear oscillatory motion this semester. I plan to build several different mechanical systems (pendula, masses on springs, etc with and without driving forces, large/ small drag, ...
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1answer
27 views

Forgotten word meaning susceptability to direction

A little over a year ago, I encountered a descriptive word with respect to experimental physics, describing the phenomenon in which calibrating an instrument from one direction will yield a different ...
2
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1answer
84 views

How to make sure that two electrons collide head to head?

In high energy experiments, people smash particles into particles. But how to make sure that they really run into each other, instead of just passing by?
2
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1answer
85 views

Why do you not get burned when you move your finger (quickly) over a candle flame?

When we move a finger quickly over/through a candle flame, why doesn't it get burned? http://en.wikipedia.org/wiki/Fire
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3answers
790 views

How to experimentally reconstruct Maxwell's equations from scratch

What are the minimal experiments would one need to perform in order to reconstruct Maxwell's equations from scratch, assuming even the concepts of $\vec E$ and $\vec B$ are unknown? While I'm not ...
1
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1answer
29 views

Switching a PMT from PC-mode to DC-mode: What happens?

I was wondering a bit how it is possible to switch a photo multiplier tube from the photon counting mode to the DC (I assume direct current)-mode. If I simply add a high voltage (as usual), I get the ...
1
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1answer
63 views

Work function definition

As in this post How would I calculate the work function of a metal, the definition is given by "the minimum thermodynamic work (i.e. energy) needed to remove an electron from a solid to a point in the ...
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0answers
166 views

Calculation of water bulk modulus using equation of state

I simply want to calculate the bulk modulus of water at 50C and increasing pressures. I think I am correctly calculating the new specific volume from the original conditions at (25C and 1atm) to 50C ...
2
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0answers
32 views

What could cause the gradual loss (or change) of power in a CO2 laser over a long period (e.g. a year)?

For example, if it were a 10W CW CO2 laser that were used for ~45 minutes per day over a period of a year. Would you expect a slight reduction in power with age? Does the dissociation of CO2 occur ...