Tagged Questions
for questions about design, process, data, or analysis of experiments and observations.
2
votes
0answers
42 views
Problem with (grad school) physics education? [on hold]
(Just to anticipate, having looked at other closed threads about physics education, I don't think this question should be too opinion based or broad.)
Since being in a lab now for a couple years, ...
1
vote
2answers
22 views
The cooling curve of tin during solidification
I'm going to measure the freezing point of tin by recording the cooling curve. It sounds like a dull experiment because all I have to do is to heat up the tin, wait for it to cool, and the computer ...
4
votes
3answers
192 views
Doesn't the use of a thermometer alter the temperature of the system?
If I place a mercury thermometer in hot water, heat energy will transfer from the water to the mercury inside the thermometer. Will this continue until thermal equilibrium is reached and thus the ...
1
vote
0answers
20 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 ...
2
votes
0answers
37 views
What are the different ways to measure the spatial curvature of the universe?
Just what the question asks. Assuming the Friedmann-Rovertson-Walker (FRW) metric, what measurements can be performed to determine the spatial curvature of the universe.
4
votes
1answer
66 views
Propagation of uncertainty when integrating or differentiating
Lets say I have a polynomial $ax^4 +bx^3 +cx^2 +dx +e$ and the uncertainties on each coefficient. Now I need to calculate the tangent at some points as well as some areas under this curve. How would I ...
4
votes
2answers
172 views
+50
Understanding the Eötvös experiment
The aim of the Eötvös experiment was to "prove" that for every (massive) particle, the quotient $\frac{m_g}{m_i}$ is constant, where $m_g$ is the gravitational mass and $m_i$ is the inertial mass.
...
3
votes
0answers
19 views
Converting impact speed to pressure magnitude
In explosive safety and stability testing, a drop test is commonly used to determine the sensitivity to impact. In the test, an impactor of known mass is dropped. The initial height varies throughout ...
1
vote
0answers
46 views
Long range repulsion in anomalous solids
As far as I know things like rocks, walls, rubber balls, polished tables etc. exert a short range repulsive force on other everyday objects that is responsible for hardness, softness, collisions, ...
1
vote
1answer
51 views
Dark matter detection
In the detection of weakly interacting massive particles (WIMPs), which is the basis of dark matter, what is the use of the tank filled with liquid xenon? I mean, how does the releasing of photons ...
1
vote
1answer
91 views
How would one test the hypothesis of human free will? [closed]
In this context, I define free will to mean that a human's high-level actions (not the quantum states of his particles) are not determined, in the same sense that some quantum effects are not ...
2
votes
2answers
40 views
How can scintillation gamma-spectrometers work given that track length is different for different angles?
As far as I understand, the basic principle of gamma spectrometer is simple - gamma ray hits scintillator, it generates number of photons which roughly proportional to gamma ray energy. Then we need ...
0
votes
1answer
29 views
experimental verification of theory
Which equation of physics could we call the best verified one experimentally? Let us define "best verified" in the sense of smallest relative error of the predicted variables. Thank you.
1
vote
0answers
36 views
What could be the distribution of an explosion energy of a mining-grade and seismic exploration explosives?
Seismic exploration involves the excitation of seismic waves using the industrially made explosive charges.
What could be the distribution of explosion energy of such a charges?
My guess is that it ...
4
votes
1answer
97 views
Experiments looking for monopoles
Background: (skip it if you know it)
In the easiest formulation of classical electromagnetism magnetic monopoles do not exist. In fact, the Maxwell's equation $\nabla \cdot \vec{B}=0$ implies (using ...
12
votes
1answer
89 views
Can a discrete dynode mass spec detector get “tired?”
In an electron multiplier (discrete dynode detector), one electron triggers the release of more electrons in a cascade.
Is it possible that a "large" number of electrons hitting the detector can ...
-5
votes
1answer
43 views
Temperature limit of the increase in heat
If the sun is the hottest known thing to humans is it possible to have a temperature greater than the sun?
6
votes
1answer
85 views
How long does it take for a chemostat to reach equilibrium?
A chemostat is a device to grow a cell culture in equilibrium.
If we denote by $x$ the cell density and by $s$ the density of nutrients, we can write down the following equations (1):
...
-1
votes
1answer
96 views
Seeing inside an atom
After seeing this photograph and reading this article : The First Image Ever of a Hydrogen Atom's Orbital Structure
I was really happy to come to know that orbitals have actually been seen now, but ...
0
votes
0answers
39 views
Choice of X-ray scatterer in Compton effect
I am going to perform an experiment on Compton Scattering, and I am going to use an X-ray scatterer to scatter the incident X-rays. I have been instructed that Acrylic Glass slab are the best for this ...
2
votes
0answers
175 views
Theoretical or experimental violations of the 2nd Law of Thermodynamics? [closed]
Theoretical challenges to the 2nd Law?
What are some the theoretical challenges to the 2nd Law?
(cf. Čápek, Vladislav, and Daniel P. Sheehan. Challenges to the Second Law of Thermodynamics: Theory ...
2
votes
2answers
38 views
Measurements from inside conductors
We have known for some time now that when electric field is applied across any conducting shell, then electric field inside it would be zero. It also has some fantastic applications such as ...
1
vote
2answers
150 views
Homework Question Transformation Energy [closed]
A $1400kg$ car is approaching the hill shown in the figure at $14.0m/s$ when it suddenly runs out of gas.
What is the car's speed after coasting down the other side?
I think I have to use this ...
-1
votes
1answer
79 views
How to detect gravitational waves?
Gravitational waves just have a little interaction with other particles. How can we detect such little influence on mass?
0
votes
2answers
59 views
1/r Counting Rate for Radiation Experiment
In an experiment performed in the lab, I want to justify that, when the width of the Geiger counter window is approximately the same size as the distance between the window and a mildly radioactive ...
0
votes
0answers
82 views
Inverse Square Law in Beta Radiation
Setup: A radioactive source is placed at alternating distances from a Geiger Counter. Counts per second for 10 different distances (each spaced 1 cm apart) were taken for preset times ranging from 200 ...
4
votes
2answers
72 views
From which side should I solder electrical feedthroughs into a vacuum flange?
I work on an experiment that requires electrical connections to a vacuum vessel, which is submerged in liquid helium (LHe). For sending the signals into the vessel, we use a feedthrough flange. I am ...
3
votes
1answer
66 views
Torque of a rotating fluid on a weighing scale
I was trying to do an experiment to measure torque (Moment force) of a rotating fluid.
I placed a cylindrical vessel of dia-12cm with 1liter of water on a weighing scale and using a spoon I rotated ...
2
votes
0answers
18 views
Expression for combining several probabilities in a single discriminator
I'm doing an analysis of some experiment. Details are not very important, but I've stumbled on an expression that I cannot make sense of.
I have several simultaneous measurements of a certain ...
0
votes
0answers
38 views
Has advanced radiation been detected experimentally?
I would like to know whether there has been an experimental detection of advanced radiation. I seem to recall reading about such an experiment but I can't find any reference to it on the interwebs so ...
0
votes
0answers
28 views
What are some common errors when it comes to measuring hall voltage of a semiconductor?
What are some common errors when it comes to measuring hall voltage of a semiconductor? I've thought of two errors:
Adjusting the potentiometer so that the width of the conductor would start with 0 ...
1
vote
0answers
35 views
Present experimental status of Moffat's Modified theory of Gravity
Modified theories of Gravity have been discussed before in this 2-year old question, Are modified theories of gravity credible?
I was going through Moffat's modified gravity, given in ...
1
vote
1answer
44 views
Curve Fitting and Multiple Experiments
Say I do an an experiment 5 times, each of which gives you a list of data points. Do I fit a curve to each one separately and then average the parameters and their uncertainties? Or do I take the ...
1
vote
4answers
220 views
Experimental evidence of Pauli's exclusion principle
A fermion is described by a set of quantum numbers, this set of numbers lead us to a unique wave function. If two fermions are described by the same wave function (violating the Pauli's exclusion ...
1
vote
0answers
67 views
Thermal Conductivity Graph
This is our first time (as an engineer) seeing this type of graph that we can't interpret.
This is a rough comparision of thermal conductivity from the Wiki page.
...
1
vote
1answer
35 views
Testing the speed of gravitational waves in superfluids
Ok. Light can be slowed down in superfluids. I would like to know whether if a Cavendish like experiment could be possible within inside superfluids i.e, to rotate two balls such that to observe their ...
1
vote
0answers
34 views
What are the current obstacles to experimentally testing quantum pseudo telepathy?
Quantum pseudo-telepathy refers to how, in some specific coordination games, isolated players can do better when they have pre-shared some entangled qubits. I understand how it works in theory and ...
2
votes
3answers
118 views
Moment of inertia of a planet
Is there a good way to directly measure a moment of inertia of the Earth, or say, other planet?
2
votes
2answers
94 views
Impossible microwave interference?
I was doing a microwave experiment with the following set up: there is a Gunn diode which emmits microwave radiation and a receiver (both work with polarised light).
The strange thing is that when ...
2
votes
1answer
64 views
Modeling Syringes e.g. with the ideal gas law
Gentlemen I have a similar yet very practical problem that might provide further insight.
I'm trying to model a moving plunger in a syringe (something like a piston in a cylinder).
At time zero the ...
1
vote
0answers
14 views
Suppose we fill a membrane with ferro fluid, and alter the magnetic field around it in specific ways, what dynamics can come into play?
im trying to develop a flexible robotic arm filled with ferro fluid. Different flexible motions can be performed using this concept.
2
votes
1answer
173 views
Calculating Expected Systematic Error in a Pendulum Experiment
I am a little confused by part c of problem 4.28 of Taylor's Introduction to Error Analysis book. A student measures the acceleration due to gravity by using a steel ball suspended by a light string. ...
0
votes
1answer
70 views
Why is it easier to measure the specific charge of an electron over the charge?
The electron was discovered in 1897 and the $e/m$ ratio was measured at that time ,but the charge $e$ itself was measured in 1911. Why was it not possible to measure it earlier?
0
votes
1answer
101 views
Coffee filter experiment: time as a function of mass
In an experiment I performed, I dropped $n$ amount of coffee filters from a constant height and recorded the time $t$ taken for the $n$ coffee filters to reach the ground. In the experiment, the value ...
0
votes
0answers
58 views
Where to find information about rocket launches (speed, height, trajectory)?
I want to find experimental data from real launches, with some description of a rocket like full mass, fuel mass, thrust and so on. Just trying to model it.
Where to read about precise methods of ...
3
votes
2answers
81 views
Questions about gravitational and inertial mass [duplicate]
What differences between gravitational mass and inertial mass? I cannot tell the differences between them.
In history, which concept was put forward firstly?
Are there some experiments to prove ...
2
votes
1answer
94 views
What is the speed of a neutral pion and how is it measured?
Alvager et al 1964 purportedly disproved Ritz's emitter theory in an experiment that generated neutral pions with a vellocity of $v =B.c$ where B is slightly smaller than one. How is the velocity of ...
4
votes
1answer
102 views
Is there valid physics behind the bodybugg?
The bodybugg is a faddish gadget whose marketers claim it can measure your body's daily energy expenditure. Their sales literature says:
As reported in the British Journal of Sports Medicine, 2008 ...
1
vote
1answer
97 views
The Higgs explains how particles acquire mass. Could it explain how much?
It's my understanding that nothing in the Standard Model predicts the mass values of the fundamental particles, so I guess that means we don't currently know how to make models of Higgs interactions ...
3
votes
0answers
127 views
Irradiation of electronic memory circuits
I am investigating the radiation hardness of electronic memory circuits (EEPROM). The following measurement has been performed:
Beam set-up:
Irradiation occurred perpendicular to the DUT (device ...
