Questions tagged [experimental-physics]

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

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Observational evidences of the early universe other than CMB

CMB is a great experimental evidence that the universe was once in an hot themal phase at early times. Supposing all the CMB observations failed for tecnical reason (for example the rocket shipping ...
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2answers
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Is the speed of quantum entanglement interaction greather than $c$? [duplicate]

How much time should not elapse between measurements of e- and e+ spin computed at a distance ot 1km to not detect effects of the entanglement? There should be a finite speed? Maybe greater than $c$?...
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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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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
64 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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1answer
80 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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61 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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2answers
64 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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How to calculate acceleration using ADXL345? [duplicate]

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
128 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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1answer
50 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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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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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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1answer
64 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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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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181 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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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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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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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
33 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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2answers
201 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
59 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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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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1answer
69 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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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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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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372 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
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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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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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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
75 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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Can we falsify photons having a tiny mass, experiencing subjective time, and traveling slightly slower than $c$ (like neutrinos)? [duplicate]

The measured speed of neutrinos can't be separated from $c$ within experimental limits. The standard model includes no mechanism to grant neutrinos mass. The mass of neutrinos can't be detected. ...
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Why was the metal lead used in the Cavendish experiment?

Is there any scientific reason why the metal lead was used in the Cavendish experiment?
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Why do my experimental data for Hooke’s law not match the expected data?

As we all know, force applied to a spring is directly proportional to the extension of spring as shown below: However, my experimental results for a simple spring from a school laboratory don't match ...
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1answer
87 views

Can regular air conditioner be used as heater? [closed]

In winter season, the normal room temperature is generally 6 to 10 degree Celsius, if the air conditioner is working at 25 degree Celsius will it be working as a heater, making the room warm (relative ...
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What are the key pieces of cosmological evidence if you want to compare the success of dark matter versus quantised inertia?

Quantised Inertia is a controversial fringe theory that is claimed to be an alternative explanation of, for example, galactic motion. The consensus explanation for why the outer stars in galaxies ...
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It is possible to have photon emission when measuring state of an atom?

Suppose in the hydrogen atom we have a state $$\Psi=a\phi_1+b\phi_2$$ where $\phi_1$ is the ground state, $\phi_2$ an eigenstate different from the ground state and $a$ + $b$ constant such that $$a^...
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1answer
31 views

Specific applications of the various modes of optical microscopy [closed]

My question is primarily about reflected and transmitted light microscopy, and the BF and DF modes in both. I am aware of the basic working principles, to state it down briefly: Transmitted light ...
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Calculating errors from given graphs

In a recent experiment, I have found the viscosity of glycerol by measuring the time it took for steel balls of measured density and radius to fall a certain distance in the liquid. Now, I need to ...
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2answers
116 views

How experimental branching fraction formula is formulated?

The Branching fraction formula for a particular decay is ${\cal {B}}(B \rightarrow X)=\Gamma_{B\rightarrow X/\Gamma_B}$. But experimentally formula is written as ${\cal {B}}(B \rightarrow X) = N_{...
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Newton constant in scalar-tensor Brans-Dicke theories

I'm reading Valerio Faraoni's Cosmology in scalar tensor theories where he says From the action (1.25) or from the field equations (1.29), one reads the gravitational coupling of Brans-Dicke theory ...
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What are the advantages of an electron-electron collider vs. An elec./positron one? Has one ever been built?

The current LHC is a proton-proton collider (instead of proton-antiproton) for reasons I have read about elsewhere. Why has there never been an electron-electron collider? Also, I am reading now ...
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Charge inside a charged hollow conducting sphere with a hole

How are the following results theoretically explained? As part of an electrostatics exercise we were to measure the charge on the outside and inside surfaces of a charged hollow conducting sphere ...
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1answer
104 views

How do we know that light travels slower in denser medium? What experiment can we do to verify it?

How do we know that light travels slower in denser medium? What experiment can we do to verify it? How did Fermat knew that light travels with different speed in different medium?
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Is the EMP threat to the power grid supported by physics? [closed]

Every once in a while I come across some article saying that our modern power grid could be knocked out of commission for up to a year by an electromagnetic pulse. I'm skeptical of such warnings. ...
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How to measure Johnson Noise precisely experimentally? [closed]

I want measure Johnson Noise across a resistor having certain over the certain range of frequency or bandwidth practically. I am starting from scratch, how can I build circuitry and instrumentation so ...
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208 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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39 views

Measuring differences in gravity based on direction of travel relative to the observer

Has there been an experiment to measure the (my vocabulary may be incorrect), intensity, strength of gravity emitted from a body, when approaching and retreating from a measuring device? If so, was ...
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How does the use of concave mirror over plane mirror advantageous in the Fizeau method of determination of speed of light?

The following text is from Concepts of Physics by Dr. H.C.Verma, from the chapter "Speed of Light", page 445, topic "Fizeau Method": One can use a concave mirror in place of the ...
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1answer
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Is there any evidence that dark matter interacts with ordinary matter non-gravitationally?

As far as I understand it, dark matter direct detection experiments are based on the idea that dark matter interacts with ordinary matter, it just has a very small cross-section. So far, there's been ...

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