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

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3
votes
1answer
151 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
0answers
60 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
votes
1answer
60 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 ...
5
votes
1answer
127 views

Measurement of cross section

When we measure the cross section of an interaction what is it that we actually measure in a real experiment? I know what cross section is and how to derive an expression for a given process but I ...
2
votes
1answer
363 views

Why are mass flow rates found using Venturi meter and pitot tube different?

Regarding an experiment to find the mass flow rate of a fluid (air) using a venturi meter and a pitot tube: What could be the cause of a variance in results obtained using the 2 instruments mentioned? ...
4
votes
1answer
181 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 ...
1
vote
1answer
87 views

What has been observed as the “Hawking radiation” emitted by a black hole analog?

I've noticed this paper which explains that they have observed the "Hawking radiation" emitted by a black hole analog. In which sense the Bose-Einstein condensate described by the paper can be ...
10
votes
1answer
208 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 ...
2
votes
1answer
41 views

How are specific volumes accurately measured experimentally?

In every thermodynamics textbook there are tables containing the specific volume of various fluids at different temperatures and pressures. My question is, how is this data obtained experimentally? ...
1
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0answers
24 views

Nuclear spin relaxation, quasi-particle energy and spin spectral density

Below is a measurement of the longitudinal nuclear spin relaxation ($1/T_1$). Ref: Fig 4 of page 24 Competing ground states in low dimensions. My question concerns the statement in this Ref that: ...
4
votes
4answers
101 views

Possibility of making an experiment in a classroom to simulate DNA diffraction

I am a TA in a structural chemistry class. The professor want me to show students how Watson and Crick determined the structure of DNA from X-ray diffraction results of DNA crystals. The professor ...
3
votes
5answers
337 views

How do we know that time dilation applies to objects other than light?

Here is a traditional derivation of time dilation: There's a train with a lamp in the ceiling, moving at velocity v with respect to an observer. In the frame of the observer, the path taken by the ...
0
votes
2answers
48 views

How are positrons produced? [closed]

What are the methods of positron production? Please don't use mathematical formulas in the explanation.
0
votes
0answers
367 views

Weight of empty versus inflated balloon [duplicate]

Will the weight of a balloon filled with air be less than, greater than or the same as the same balloon after it has been deflated?
11
votes
1answer
560 views

The status of the BICEP2 'discovery' after Planck 2014

The tumultous period after the original announcement that the BICEP2 experiment had supposedly detected strong evidence of cosmological inflation in the form of B-mode polarization in the cosmic ...
5
votes
0answers
94 views

The use of Artificial Intelligence in physics resarch

I have been reading about a machine that observed a double pendulum and created equations that both described its motion and associated conservation laws. The authors claims: We have developed a ...
14
votes
3answers
936 views

What is the most compelling evidence of General Relativity in the presence of matter and energy?

The most oft-cited triumphs of GR are things such as the shifting perihelion of Mercury, gravitational redshift experiments, and gravitational lensing. But, as far as I know, these are only ...
0
votes
2answers
56 views

At what point do researchers in physics make the leap from wild theoretical ideas to physical experiments? [closed]

Dark Matter, on the surface, appears to be a wild idea... Some invisible thing that we can't see that controls the movement of most of the universe. Yet, we are searching for it. Why? What evidence ...
1
vote
1answer
74 views

Research papers readable by first years? [closed]

This coming Spring I'll be running a Mechanics I lab for freshman (as a teaching assistant) and I'll have some say as to the way I do it. So I was thinking it would be nice if I could find some ...
0
votes
0answers
9 views

how to completely remove the charge from the glass bubble particles?

Do you have any idea on how to completely remove the charge from the glass bubble particles (25-32 micrometer diameter)? Thanks
4
votes
1answer
110 views

Can LIGO measure anything?

LIGO, Laser Interferometer Gravitational-Wave Observatory, is a large-scale physics experiment aiming to directly detect gravitational waves. The device measures the phase shift laser beams. If I ...
0
votes
1answer
211 views

Ways to measure the focal length of a convex lens with only natural sun light [closed]

What are the common ways to measure the focal length of a convex lens with only natural sun light?
2
votes
0answers
21 views

How to measure the permittivity of a gas sensor? [closed]

I looking for a simple method to measure the permittivity of a gas sensor silicone.
0
votes
2answers
69 views

Experimentally, what categorizes a measurement as corresponding to a certain observable?

I want to write a computer program. The input to the program is: A description of an experimental device (for instance a Stern-Gerlach apparatus, or a laser and a polarizer) What the experimenter ...
0
votes
0answers
24 views

Hydrogen spectrum intensity using a monochromator

Using a monochromator (350->800 nm) and a hydrogen gas lamp, I find this spectrum : We can see 3->2, 4->2, 5->2 transitions from Balmer series, but not 6->2 (which we should expect at 410 nm). As ...
2
votes
2answers
79 views

Weighted mean from data [closed]

Suppose we have 3 experimental groups measuring "x", they measure $$x_1=\mu_1\pm \sigma_1$$ $$x_2=\mu_2\pm \sigma_2$$ $$x_3=\mu_3\pm \sigma_3$$ In the 3 experiments, we have done N measurements of ...
4
votes
1answer
267 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 ...
-1
votes
1answer
143 views

Emission and absorption of photons by electrons [closed]

Two questions occur at a critical review of the two famous experiments devised by Millikan in 1914, respectively Duane, Hunt and others in 1917-1920, which confirmed the action constant calculated by ...
0
votes
0answers
21 views

Air Cylinder to drive Pneumatic Pump

I am required to drive a pneumatic chemical injection pump using Compressed Air in Cylinders. The pump requires a supply pressure of 80 psi to effectively ensure. We do not have a flow meter to ...
1
vote
2answers
95 views

How are the components of the spin vector defined?

How do we distinguish between the $x$, $y$ and $z$ spin components? More precisely: how do we define the $z$ component? (according to what, it is the $z$?) for measuring the $x$ component how ...
2
votes
1answer
219 views

What is the error in a ruler?

I'm having trouble understanding simple error analysis of a ruler. Suppose we have this ruler. There is a mark for every centimeter. The precision is half a centimeter. This should mean that the ...
-1
votes
1answer
76 views

How to entangle two particles? [duplicate]

After learning about quantum entanglement I wanted to know, what is the simplest way to entangle two particles in a lab?
5
votes
1answer
636 views

Gravity is curved geometry: A fact of nature or model-dependent interpretation?

We are regularly taught in high-schools and universities that, according to General Relativity (GR), gravity is nothing but a manifestation of space-time curvature (which, in its turn, is caused by ...
1
vote
0answers
61 views

Books on experimental methods, fluid mechanics related

I need some good books on experimental methods, requirements are: Fluid mechanics related; Thermal, multi-phase etc. topics should be covered; Traditional methods are good, but it would be greater ...
0
votes
1answer
93 views

What is the general definition of signal acceptance?

Suppose I have a beyond Standard Model theory and want to test it. I want to test if some experiments, say conduced in LHC, show signals of the theory. In this case, what is "signal acceptance"?
0
votes
0answers
17 views

An experiment in quantum theory involving a metal ring

I'm trying to remember the name of an experiment that I saw on YaleCourses in a lecture by Professor Shankar. My recollection is that something was sent around a closed metal ring. The fact that the ...
0
votes
0answers
38 views

Definition Of Dark Current In PhotoDetectors

What is The Definition of Dark Current In PhotoDetectore. How Can I Eliminate This Effect. I Think When Electrons Near The Conduction Band Are Excited Into It By Thermal Effect Then Dark Current Is ...
9
votes
3answers
2k views

How did Rutherford's gold foil disprove the plum pudding model?

What stops one of the two following scenarios from happening, consistent with the plum pudding model? The $\alpha$ particle, attracted by the electrons on the outer shell of the pudding, orbits ...
1
vote
1answer
27 views

Experiment Equipment Supplier (for use in the Classroom & at Home) [closed]

Does anyone know of an online store that sells equipment specifically designed for carrying out demos in the classroom or at home? I'm helping out a student taking college physics and chemistry. These ...
12
votes
1answer
289 views

What is the relationship between Faraday cage mesh size and attenuation of cell phone reception signals?

This is related to the question how can electromagnetic waves reach a cell phone in faraday cage?, where in the answer it was stated that the holes (=size of the mesh) would need to be smaller than ...
1
vote
1answer
39 views

Uncertainty of approximately sinusoidal voltage measurement

Say one is interested in measuring the mean value an approximately sinusoidal voltage with an instrument that has an accuracy of 0.01 V, according to its spec sheet. 10 periods of the oscillation have ...
1
vote
0answers
67 views

What is a good book describing the major experiments in Quantum mechanics? [closed]

I need some book suggestions on few of the major experiments done in Quantum Mechanics which are important in terms of what they imply, how they prove or disprove any theory that still exists or was ...
1
vote
2answers
71 views

Do bad clocks measure proper time?

It has been claimed several times e.g. here, and here, also here, or (outside PSE) there that Clocks measure proper time. Or equivalenty: proper time is just the time that would be ...
0
votes
1answer
762 views

Effect of varying distance of light source from a Light Dependant Resistor

I'm doing the experiment described here and I have a few questions about it. I have a miniature light dependent resistor (LDR) hooked to a multimeter set to $\Omega $ and a $25\,\mathrm W$ Light ...
0
votes
1answer
43 views

Determine reactance force of four load cells arranged in two dimensions

I have constructed a "force plate" to reconstruct the location (x,y) of a steady state contact point force f. The system consists of four fixed compression load cells L1, L2, L3, and L4 and a thick ...
2
votes
1answer
42 views

Energy resolution of LHC Electromagnetic Calorimeter

So I am trying to get an estimate of the electromagnetic calorimeter resolution at LHCb, and I have found this online: But I have no idea of what it means. Can anyone explain what the last part ...
1
vote
0answers
23 views

Stop CO2 laser firing through holes in glass

How would you prevent a CO2 laser with interlocks used to mark glass from firing if there were holes in the glass. Usually the interlocks prevent the laser from firing unless it is pressed against ...
0
votes
3answers
161 views

If a tree falls in the forest [closed]

The question of whether or not a tree that falls in the forest makes a sound - if there is nothing or no one around to hear it - comes up frequently at my house. So, my question is: is there any way ...
0
votes
1answer
96 views

Photoelectric effect experiment: is charging time proportional to current?

I'm not really sure what tags to add to this question, but definitely this is just an introductory physics experiment. Let me refresh you first with the basics of the photoelectric effect. We all ...
2
votes
2answers
109 views

Is a Thomson's lamp physically realistic? [closed]

The Thomson's lamp is a philosophical puzzle that can be describe as follows: Consider a lamp with a toggle switch. Flicking the switch once turns the lamp on. Another flick will turn the lamp off. ...