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

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0answers
71 views

Why does randomness exhibit a pattern in the long run? [migrated]

!!! Layman here so please avoid complex math and answers. Random (usually pseudorandom) events are usually characterized along these lines: Each outcome in a trial experiment must be i.i.d.; i.e. ...
2
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1answer
53 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
13
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3answers
735 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 ...
4
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2answers
322 views

How many sigma did the discovery of the W boson have?

When the W boson was discovered in the 1980s, nobody spoke of sigmas. How many sigmas was it at that time?
2
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1answer
204 views

Rutherford Experiment - practical and theoretical questions

I performed the Rutherford experiment the other day, using Au thin foil of $2\,\mathrm{\mu{}m}$, a source/gun of α particles (241Am) and a detector/counter. α particles were shot from the source ...
7
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2answers
526 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 ...
3
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1answer
112 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
252 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 ...
2
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4answers
98 views

What's the difference between frequency domain and time domain spectra?

If I have a mechanical oscillator and want to observe the dynamical behavior of the oscillator, is there any additional information to observe it in time domain and frequency domain? Normally, we ...
12
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2answers
3k views

How do we know that some radioactive materials have a half life of millions or even billions of years?

If a radioactive material takes a very long time to decay, how is its half life measured or calculated? Do we have to actually observe the radioactive material for a very long time to extrapolate its ...
1
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1answer
23 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
43 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 ...
4
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0answers
106 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 ...
4
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1answer
164 views

Model Selection in Physics [closed]

My high-level understanding of the scientific method is that it can be summarized in the following steps, in no particular order: Make conjectures & hypotheses (theory) Make predictions ...
2
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0answers
26 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 ...
24
votes
2answers
660 views

Status of experimental searches for tachyons?

Now that the dust has settled on the 2011 superluminal neutrino debacle at OPERA, I'm interested in understanding the current status of experimental searches for neutrinos. Although the OPERA claim ...
3
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0answers
285 views

Pockels effect/Kerr effect

In Pockels electro-optic effect, change in Electric field produces change in refractive index/ birefringence. Moreover this effect becomes electric field squared in the case of Kerr effect. If we ...
1
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1answer
106 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 ...
4
votes
1answer
159 views

Why is the relationship between velocity and radius curved, in circular motion?

We are supposed to graph velocity squared against period. My instructor specifically said: The gradient of this graph is acceleration and We should observe a trend of decreasing orbital velocities ...
2
votes
1answer
45 views

How did Kepler formulate his second law from data?

It's amazing that Kepler derived his three laws emperically and then Newton rederived them from his own laws of motion. Its conceivable how Kepler derived the first and third laws, but the second law? ...
3
votes
3answers
448 views

Has $E=mc^2$ been experimentally verified for macroscopic objects with potential energy?

In relation to this question: What is potential energy truly?, I'm wondering if $E=mc^2$ has been experimentally verified to hold true for macroscopic objects with increased potential energy? I'm ...
1
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1answer
57 views

What are the methods of experimentally measuring the observables in quantum mechanics?

Perhaps due to the limited number of textbooks on quantum mechanics I have consulted, I have seen presented the fundamental principles related to observables, but have never seen a somewhat systematic ...
0
votes
2answers
33 views

Theoretical uncertainty of a circuit's total resistance when made entirely of resistors

My question in short(ish) is: Will the fractional uncertainty of a circuit made entirely of resistors with equal fractional uncertainties be the same as the fractional uncertainty of those resistors. ...
0
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0answers
34 views

Errorbars for data series with variable number of points and several layers of uncertainty

I'm making a 2D plot of my microwave S Parameter data and want to represent the error bars correctly. Experimental Context: I measure S21, (Vout/Vin), as a function of frequency and drive power with ...
1
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1answer
36 views

Why does the surface structure of a metal make it hydrophobic?

I was just reading this article from phys.org describing water-repellant surfaces. However the article doesn't go into enough details of explaining why a particular structure repels the water. Can ...
6
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5answers
2k views

Evidence that stationary masses in space actually attract each other

I'm finding it rather difficult to find experimental evidence that two stationary masses in space (unaffected by external massive bodies or gravities) actually attract one another. For moving masses, ...
0
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0answers
37 views

Insulation for magnetic fields [duplicate]

How can I insulate conductors independently one off the other, where they pass through a magnetic field? Are there a techniques or alloys? There is a issue how to insulate copper wire where current ...
3
votes
1answer
44 views

What does 'channel' mean?

I see many plots like the following that graph counts per channel, I know what a 'count' is, but I don't know what a 'channel' is. Could somebody please explain to me? My guess is that it is that ...
3
votes
2answers
261 views

How do you measure wavelength/frequency of light

I'm sure this is a trivial question for someone who knows something about electromagnetic radiation, but: how do experimenters measure the wavelength/frequency of light? For example, how do we know ...
1
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0answers
35 views

Born-like measuring rule in classical experiments

this 2011 paper "Born's rule from measurements of classical signals by threshold detectors which are properly calibrated" by Khrennikov investigates the theoretical possibility of Born-like ...
2
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0answers
22 views

What material could be used to study magnetic phase transitions in a college laboratory exercise?

I am working to develop a simple laboratory exercise in solid state physics to be conducted by fourth year students of physics. The idea of the exercise is for the student to get some experience in ...
7
votes
3answers
174 views

How to reproduce highway vibration?

I would like to test my hardware under vibration that can appear on a highway gantry. If someone has a model of such vibration. i.e period and amplitude. In my lab I have a motor that can be ...
0
votes
0answers
22 views

What experiments of a high school standard are there to investigate the magnetoelastic effect?

I've ended up investigating the reverse magnetostrictive effect for coursework, which is 30% of my grade this year. I started by hitting a magnet with a hammer (on the recommendation of my teacher) , ...
390
votes
20answers
144k views

Cooling a cup of coffee with help of a spoon

During the breakfast with my colleagues, a question popped into my head: What is the fastest method to cool a cup of coffee, if your only available instrument is a spoon? A qualitative answer would ...
3
votes
1answer
97 views

Should gravitational waves be discovered already?

Gravitational waves are not discovered directly (yet). But does this have any consequences? Should we suspect out theories are wrong or not yet? I found some data about gravitational waves suspected ...
2
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0answers
21 views

How to distinguish Shake-Up Satellites from Plasmons?

I am studying XPS spectra (X-ray Photoelectron Spectroscopy) at the moment. In XPS, different processes can influence the final state energy of detected electrons. One of these processes is the ...
0
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0answers
16 views

Help Interpreting Ultraviolet Photoelectron Spectroscopy (UPS) data

I was given a batch of UPS data without any background other than the materials examined and I don't have any experiencing interpreting it. I wanted to reach out to some experts (hopefully, someone ...
0
votes
2answers
48 views

Photon yield of NaI

We have to calculate the photon yield of the scintillator NaI. We have measured his pulse height spectrum but we have no idea how to solve this problem. Can someone explain it? The source that we used ...
3
votes
1answer
94 views

Tunable Optical Band Pass Filter

Is there any cheap method by which to create tune-able optical band pass filter? I am working with a chemical process which will fluoresce when excited by a specific wavelength of light. As shown in ...
0
votes
1answer
45 views

Measuring depth or height from sea level

How is the depth or height relative to sea level measured? Well, if it's near the ocean, it can be easily measured manually, but what if it is 100 km away from the sea? What method is used?
-1
votes
1answer
26 views

will my duraflex seams melt over a fire

Good day ladies and gentlemen, i do realize it may seem like a welding question but i assure you it is physics related. i have built a non pressurized boiler that contains water to be used over an ...
5
votes
2answers
453 views

Why do we hear lesser noise when plastic bags/wrappers are crumpled inside water than when they are crumpled in air?

When plastic bags/wrappers are crumpled in air they make noise. But when crumpled inside water we hear very little noise. Why is it so? Would I hear more noise if I go inside water and crumple the ...
1
vote
2answers
25 views

Determining the behavior of the transference function as $\omega\to 0$ or $\omega\to\infty$

I'm studying experimental Physics and one of the experiments I must understand is about electronics concerning filters. Considering one RLC filter, measuring the output at the resistor we have the ...
0
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0answers
23 views

Static Friction on Windmill?

If I know the wind speed applied to the windmill, and the time it takes to start moving, is there any way to calculate the static friction?? Also is there any way to calculate the force of the wind? ...
5
votes
3answers
1k views

Why can't echoes be heard inside a room?

If I go camping and shout anywhere, in the forest or on a cliff, I usually hear the echo of my voice. Why when I shout in my room I do not hear any echoes?
0
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0answers
41 views

Summing up independent mass measurements to recover $Z$ boson mass

I am trying to calculate the $Z$ boson mass from a list of $\mu^+\mu^-$ data (momentum). We have been asked to make five blocks of data from the total amount of 10k. Then calculate the mass via ...
0
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0answers
35 views

faraday's rotation for revealing hidden text

I'm trying to come up with a twist on the known faraday's rotation experiment involving a laser projecting into a polarizer. the polarized light then passes in a selenoid containing a glass rod. the ...
0
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0answers
51 views

Can high osmotic in nerve, intracellular concentration, lead to 'pumping up' nerve cells, strongly increase internal pressure, myelin sheath broken?

On: http://biology.stackexchange.com/questions/6916/can-in-the-case-of-multiple-sclerosis-ms-a-too-high-osmotic-pressure-in-the-n I read a question: Can in the case of multiple sclerosis (MS), ...
0
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1answer
42 views

What are the preferred height and diameter proportions for a rocket model?

I'm pretty sure, that if you make a rocket that's relatively small in height compared to diameter, it will most likely not fly very high and probably spin out of control. What about a rocket that is ...
10
votes
1answer
173 views

Microtops sunphotometer sun target optics

For atmospheric radiation observations, a portable piece of equipment such as the Microtops sunphotometer (pictured below) is useful. Image source: Solar Light However, while I can borrow this ...