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

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2
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5answers
127 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
42 views

How are positrons produced? [on hold]

What are the methods of positron production? Please don't use mathematical formulas in the explanation.
0
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1answer
31 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?
10
votes
1answer
192 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
43 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 ...
0
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0answers
38 views

Upper division physics lab — Project ideas [closed]

As an experimentalist, I am very excited to be taking my first upper division physics lab next semester! The course covers basic electronics (filters, diodes, transistors, op-amps, analog & ...
13
votes
3answers
855 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
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2answers
47 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
62 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
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0answers
4 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
3
votes
1answer
92 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 ...
-1
votes
1answer
38 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
16 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
54 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
12 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
64 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 ...
3
votes
1answer
110 views

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

An experiment to model planetary motion: The brown rubber was supposed to model a planet, while we varied the radius $r$ and the mass hanging from the string. Varying the masses was to show ...
-2
votes
1answer
75 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
7 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
40 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
42 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 ...
0
votes
1answer
57 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?
3
votes
1answer
585 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
26 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
21 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
14 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
13 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
1k 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
16 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 ...
8
votes
0answers
64 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
19 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
46 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
56 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
0answers
51 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 regarding it. I've taken a mini-LDR hooked to a multimeter set to $\Omega $ and a $25\,\mathrm W$ Light Bulb to plot the following ...
0
votes
1answer
17 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
25 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
16 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
111 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
29 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
101 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. ...
2
votes
1answer
93 views

What is the smallest length scale ever measured?

And, by the way, what is, or are, the measured values?
2
votes
2answers
57 views

How to identify a “measuring rod”, and how to compare separated “measuring rods” with each other?

The notion of "measuring rod" has appeared in PSE here and there, and outside PSE as well. As far as I understand (and as perhaps all who refer to this notion do agree on), important constituents of ...
2
votes
3answers
76 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 ...
3
votes
2answers
57 views

How is the most accurate value of $G$ measured?

How do modern scientists update the measurement of $G$, the gravitational constant? Is CODATA the authority on this measurement and the experiment?
3
votes
1answer
92 views

Inexplicable Results in a Vacuum Experiment

We've been doing the following experiment in our Physics Lab course and are coming up with some strange results which we're at a loss to explain. The purpose of the experiment is to determine the ...
1
vote
0answers
18 views

Mixing liquids when applying a voltage

I'm thinking in the following experiment: A) Two (non mixable (like water and oil)) liquids are going to lie in a container, in the extremes of the container there are two electrodes, those ...
1
vote
2answers
73 views

Does a Michelson-Morley experiment uphold mass-energy equivalence and special relativity?

If there is an experiment that best supports $E=mc^2$, is it the Michelson-Morley experiment?
0
votes
0answers
20 views

How is 2D spectroscopy able to show quantum coherent transport through networks?

For wave-like (quantum coherent) energy transfer in networks (eg. propagation of excitation in photosynthetic protein complexes of algae or FMO complex in plants) 2D electronic (photon echo?) ...
0
votes
0answers
12 views

Can “uniform motion” (or “mutual rest”) be determined intrinsically, by members of Synge's “five-point curvature detector”?

In his description of a "five-point curvature detector" [1], J. L. Synge exhibits a Cayley-Menger determinant in terms of "optical distances" between five distinct participants; and he states that the ...
6
votes
1answer
108 views

How legit is this paper claiming to have observed Hawking radiation? [closed]

I recently stumbled upon this paper. In it, the author claims to have found a signature for Hawking radiation in a condensed matter system. I know that experimentalists have been trying to find ...