Questions tagged [experimental-physics]

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

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Why is that? repulsive forces and attractive forces

These are the upper and lower discs A and B. There is a small hole in the center of A, and a pipe is connected to the small hole. The pipe is connected to compressed air. We use B to approach A. ...
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8answers
6k views

Given fluids expand non-linearly, how were physicists able to make a linear temperature scale?

Materials expand with increase in temperature. As far as I know this property for fluids was put in use to make initial thermometers. We know that expansion of fluid is given by the following formula (...
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1answer
38 views

How does one create a polarized beam of particles?

I want to know how experimental physicists create spin-polarised beams of particles, say electrons, muons or quarks. My first guess is that one would polarise such a beam in a magnetic field. The two ...
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4answers
207 views

Has the Michelson-Morley experiment been performed while moving in relationship to Earth?

I'm currently trying to debunk some geocentrist claims the Michelson-Morley experiment proves Earth isn't moving and I'm wondering - has this experiment ever been performed while in motion relative to ...
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4answers
3k views

What does the $I$-$V$ curve in josephson junction mean?

According to the $I$-$V$ curve for Josephson junction tunneling for S-I-S (superconductor-insulator-superconductor), Do we have any tunneling current for $0< V\leq V_c$? If yes, then why don't we ...
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1answer
33 views

What are the minimum/realistic energies needed for positron/electron annihilation to form $D$ mesons?

High energy positrons and electrons can form $D$ mesons when they interact with each other and annihilate, but I was wondering what those energy levels would have to be. Specifically, would a fixed ...
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2answers
199 views

Why does concave mirror simultaneously form two images?

In an experiment to find focal length of a concave mirror, first we had to estimate its rough focal length. I kept an object at point which was beyond the focus in front of the mirror and got its real ...
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1answer
165 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 exposed....
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11 views

I have a percent loss of the power output of a PV cell that isnt 1 meter squared. How can I aplpy the power loss to other panels

I made an experiment were I added sand ontop of a PV panel and measured the decrease in power output. I graphed the percent loss of the power output from when there was no sand. My panel isnt 1 meter ...
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1answer
76 views

Does more and more measurements of $X$ indefinitely improve $\sigma_X^2$?

For a physical quantity $X$, does the standard deviation $\sigma^2_X\equiv\langle X^2\rangle-\langle X\rangle^2$ calculated from $N$ measurements smaller than that calculated from $N^\prime(<N)$ ...
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1answer
40 views

Resonance Frequency and Centre of Gravity

Is there a relationship between these 2 As of now I am moving a piece blutac up and down a ruler to change my COG. I have connected the base of my ruler to a vibration generator and am measuring the ...
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7 views

Molecular Astrophysics Vs Astrochemistry [closed]

How the molecular astrophysics field different from Astrochemistry?
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11 views

Technique to measure distance between two conductive plates using a type of EM Radiation [closed]

Pertaining to an experiment of my Universities enterprise team, Can anyone brainstorm a technique to measure the distance between two conductive plates, one-on-top of the other, separated by a ...
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1answer
68 views

Dependence of resonant frequency on the length of a ruler

Why does the resonance frequency of a ruler increase when the length is lower? I have a relationship from experimenting but I want to know why. I have a vibration generator hooked up to the bottom ...
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0answers
48 views

Why are rare decays a good probe for New Physics?

It is often said that decays that are suppressed by the SM are an excellent probe for searches for New Physics. Why is that the case? I understand that if a process is forbidden by the SM, such as ...
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1answer
308 views

Definition of contrast-to-noise ratio?

I have been looking at definitions of the contrast-to-noise ratio. As indicated in numerous sources (e.g. here (page 12)), the contrast to noise ratio between two signals $A$ and $B$ is: $$ CNR=\frac{...
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36 views

Finding the focal point of a converging lens using cello tape. What could be the physics behind this technique?

Given a converging lens of unknown focal length, one can use a cello tape to roughly estimate the focal point of the lens experimentally. In the laser beam path after the lens, the converging beam ...
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2answers
37 views

Does salt water melt faster or slower than pure water?

I am trying to conduct an experiment on the melt time time of two ice cubes with a different salt concentration, one with none and one with a lot. Does salt water melt faster than pure tap water? (...
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1answer
123 views

Analytic Solutions to Magnetic Fields of Circular Current Loop

I came across an interesting problem and am wondering if there is a quick answer to it from someone who's done this before before I whip out the books of integral tables. Analytic expressions from ...
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0answers
22 views

How to calculate acceleration using ADXL345?

I am trying to measure the acceleration and deceleration of a bike by using an 3 axis accelerometer (ADXL345). I know the formula of calculating acceleration using the $x,y,z$-components with respect ...
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1answer
158 views

Measurement of quark's spin

Since quarks always form bound states, how do we know the spin of a single quark is $\frac{1}{2}$ experimentally?
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1answer
45 views

If a device's uncertainty for measuring time is $ 10^{-4} $, what happens to the uncertainty when the experimental value is squared?

In a case where the device's uncertainty is found to be $ 10^{-4} $. As it is a device that measures a time interval; when squaring the experimentally obtained value, what should one do with the ...
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2answers
102 views

Should a graph of $T^2$ against Mass pass through the origin? Pendulum/spring constant [duplicate]

[NOTE to reviewers : Voting to reopen because duplicated question was posted by same user and was closed without answers. This question has been edited in the hope of removing any lack of clarity.] I ...
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1answer
56 views

Sensitivity of observables to New Physics

I am currently reading a PhD thesis on experimental particle physics and at some point the author talks about the sensitivity of a given observable $Q$ to New Physics (NP). The idea is that ...
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25 views

Refractive index values of the solution less than that of the solvent. Why does that happen?

I have been doing an experiment for finding the third-order nonlinear susceptibilties of organic molecules using Degenerate Four-Wave Mixing (DFWM) at femtosecond regime. For the calculation of the ...
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2answers
212 views

Are there experiments that deal with the headlight effect?

If I am not mistaken, the Ives-Stilwell experiment measures the frequency of emitted light to test the relativistic doppler formula. Is there anything like this for light intensity? Have we measured ...
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1answer
155 views

Ohm's second law: step by step to obtain this law [duplicate]

Ohm's second law is valid only if the electric current is evenly distributed in the section of the conductor, i.e. in the case of direct electric current and its relation is the following as we all ...
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62 views

Meaning of *supersaturation* in diffusion cloud chamber

While trying to build a diffusion cloud chamber using the "classical" Langsdorf method, which employs a cold plate to create a steep negative temperature gradient, inducing supersaturation in alcohol ...
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155 views

How was the mass of the moon first calculated?

How was the mass of the moon first calculated? How do we measure it now?
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15 views

membrane for a reverse osmosis desalination experiment

We are second year cram schoolers , we are currently working on a project tackling water desalination by reverse osmosis and are required to do an experience. During the process, we encountered some ...
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70 views

Solving simultaneous non-linear equations [closed]

I am working on a problem in infrared spectroscopy. I have an unknown function of transmitter receiver distance, $a( d )$, which I want to determine for several fixed distances. I have an unknown ...
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2answers
241 views

Example of experimental or observational proof of quantum indeterminacy before measurement

How do we know that certain properties are indeterminate or undefined until they are measured? Take the example of quantum entanglement, saying that if you have two entangled particles, such as the ...
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2answers
187 views

Closed Room Experiment to prove Earth isn't flat

With Focault's pendulum, it is possible to demonstrate in a closed room that the Earth Rotates with respect to an inertial reference frame. And allowing guests to inspect and manipulate the pendulum ...
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1answer
28 views

Why does a bottle under pressure resonate better than one at ambient pressure?

Consider a plastic soft drinks bottle. Shake it up so that it fizzes and pressurizes the environment inside the bottle. Tap the side of the bottle, and it'll make a low bing sound. Now open the ...
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17answers
7k views

Can a mathematical proof replace experimentation?

I know that this is very similar to How important is mathematical proof in physics? as well as Is physics rigorous in the mathematical sense? and The Role of Rigor. However, none of the answers to ...
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34 views

Super Kamiokande experiment with atmospheric neutrinos

Why did the super Kamiokande experiment see half the rate of atmospheric muon neutrinos from below than from above, but the same rates from electron neutrinos? It seems like it has to do with ...
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6answers
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Which experiments prove atomic theory?

Which experiments prove atomic theory? Sub-atomic theories: atoms have: nuclei; electrons; protons; and neutrons. That the number of electrons atoms have determines their relationship with other ...
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1answer
46 views

Changing hot-filament SEM electron source into field-emission one

MOTIVATION: The resolution of scanning electron microscope (SEM) images is limited by multiple factors, one of them being relatively low electron-beam current density emitted by cheap tungsten ...
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1answer
66 views

Passive dissipator block between two peltier cells seemingly raising overall temperature differential

I am experimenting with stacked Peltier cells trying to build a simple diffusion cloud chamber. I noticed that when simply stacking two peltier cells the upper side reaches a temperature (around -15 C)...
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25 views

What is the current state of the muon $g-2$ experiment at Fermilab?

What is the current state of the muon $g-2$ experiment at Fermilab? The last time I read about it, the $g-2$ factor was only correct upto 8 decimal places as calculated by QED which was less than that ...
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12 views

How is the intrinsic parity of the photon measured?

How do we know experimentally that photons have intrinsic parity $-1$? I know about the Wu and Shaknov experiment, but i cannot find any detailed information anywhere.
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334 views

Quantum gravity experiment with BEC

This paper Exploring the unification of quantum theory and general relativity with a Bose-Einstein condensate proposes using a BEC in a superposition of two locations to test gravitationally-...
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1answer
26 views

Are the measurement outcomes of an observable gaussian distributed?

Suppose in an experiment we perform $n$ independent measurements to find the true value of an observable $X$. Let the outcomes of $n$ measurement are denoted by $x_1,x_2,...x_n$. If $n$ is ...
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1answer
32 views

When was the speed of a bullet or cannon ball first measured? [closed]

I see that prior to the invention of accurate clocks it might have been pretty hard and I wonder, just as with the speed of light, the speed of bullets was wildly over-estimated.
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12 views

Oppossing Laser Beams Cause One Beam to Disappear [duplicate]

I posted a video early where I asked the question about opposing laser beams appearing to turn one laser off. Further experiments, however, have demonstrated that it is interference at play not that ...
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1answer
71 views

Which was the fastest speed relativistic momentum equation $p = γmu$ was tested?

I was reading Tests of relativistic energy and momentum and Momentum , and if I understand correctly they mention tests of relativity and the equation $$p = \gamma mv$$ $$\gamma = \frac{1}{\sqrt{1 −\...
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1answer
209 views

“Modern Presentation” of Observations on Phase Transitions

In the introduction of Introduction to QFT by Peskin and Schroeder, the authors write "we do not discuss the beautiful and varied experiments on phase transitions that led to the confirmation of field ...
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2answers
3k views

The coin drop experiment

There is an experiment called coin drop. You have a glass and a coin on top of a surface such as a paper. When you move the paper slowly the coin remains on it but when you move it really fast the ...
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In the laboratory, is it possible to make a spherical ball uniformly charged?

Note: This question is about experimental physics. So it seems to me that this question is on topic. In the laboratory, is it possible to make a spherical ball uniformly charged? (like by : ...
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1answer
275 views

RF-sputtering: where comes the target self-bias voltage from?

While learning for an exam, I stumbled over the following Question: According to Material Science of thin Films by Milton Ohring, "RF sputtering essentially works because the target self-biases ...

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