Questions tagged [experimental-physics]

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

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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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31 views

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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2k views

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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20 views

Uncertainty in elevation software [closed]

so I'm trying to use the barometric formula for my lab project for better accuracy in my results. In this equation I need of course the height above sea level , which I was able to find using numerous ...
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2answers
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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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2answers
79 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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28 views

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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32 views

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
27 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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2answers
33 views

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
54 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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Using three MCA ADC IN inputs in Multiport II Canberra module - nuclear electronics

For a nuclear physics experiment I want to use three ADC IN inputs of "Multiport II (Canberra)" module simulatenously - one will be logical input coming from "Gate & Delay Generator" (416A Ortec) ...
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2answers
995 views

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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41 views

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
95 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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127 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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2answers
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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19 views

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 plane mirror [...
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1answer
6k views

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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2answers
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running on the outside of a moving train

Seen a few films lately where the hero runs on top of a moving train, for example "Under Siege 2". It gives the impression that the train is moving quite fast (presumably its normal operating speed on ...
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1answer
45 views

Light Bulb Resistance

If the voltage and current of a circuit containing a light bulb are measured using a multimeter after consecutively lowering the voltage (building of a data set), what (type of) function will describe ...
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44 views

Coulomb Barrier - Nuclear Physics

When we calculate the Coulomb's barrier we usually assume that two nucleus (target and projectile) just touch each other so the barrier: $$E_{cb}=\frac{0.96Z_1 Z_2}{A_1 ^{1/3}+A_2^{1/3}}\text{ MeV} \...
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Statistics and data analysis book for physics student(introductory level)

I am a physics undergrad student and I want to learn statistics and data analysis from the point of view of usefulness in physics (be it stat mech, experimental physics, theoretical physics). Could ...
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3answers
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Why transcendental terms in the laws of nature are dimensionless?

Through my years in nuclear engineering, it has always been the case that in physical relations, the arguments of transcendental functions, e.g., the exponential in the law of radioactive decay, $N=...
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Non-neutral plasma axial vs radial timescales in Penning-Malmberg trap

I have been reading about trapped electron plasmas, and computer simulations for plasmas in Penning-Malmberg trap. Can somebody help me to understand why the timescale for radial transport is much ...
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1answer
64 views

Why does this sine wave like pattern appear in cut plastic?

I was opening a package that was plastic wrapped from the super market with the prong of a fork, and this pattern (in the picture) emerged: I started by poking the prong of the fork (right side of ...
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47 views

A Physics Book for Experimental Evidence

I have come to notice how Physics is developed: we do some experiments and (from them) draw concise conclusions, which we call physical laws. Then we come up with the appropriate mathematics to—fully ...
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1answer
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In neutrino oscillation experiment, what are the Feynman diagrams involved for the *detection of the neutrino* in the detector?

In neutrino oscillation experiment, for example NOvA [but it could be other if you prefer], what are the diagrams involved for the detection of the neutrino in the detector ? I have explored inside ...
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2answers
113 views

Will state of water change in certain condition? [closed]

Imagine I have an iron tank with a $20~\mathrm{pm}$ hole on it. Then I completely fill it with water and use a pump to get the water out of that hole. What will come out, water or gas?
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Why is a leading digit not counted as a significant figure if it is a 1?

Reading the book Schaum's Outline of Engineering Mechanics: Statics I came across something that makes no sense to me considering the subject of significant figures: I have searched and saw that ...
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1answer
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Where can I find the original experiment that lead to this discovery of “new fundamental underwater force”?

I read this article Discovering a new fundamental underwater force which describes the discovery of the mechanism that causes particles in stratified fluids, e.g. the oceans, to move towards others ...
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25 views

Guoy method derivation, or, how not to break math?

I start from $d\vec{F}=\nabla(\vec{m}\vec{B})$, $\vec{M}=\frac{d\vec{m_i}}{dV}$, and $\vec{M}=\frac{\chi_v}{\mu_o}\vec{B}$. I write out the definition of the force, determine we're only interested ...
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1answer
37 views

Distance between laser diode and photodetector

I have a laser diode with a wide divergent elliptical beam (angles: 57°-13°). If I want to use a light detector with 50mm diameter, how can I estimate the distance at which I can put the LD from the ...
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2answers
97 views

Why is the the positively charged electrode referred to as the anode in this apparatus?

In this image taken from the manual of the NaRiKa/Nada Scientific EM-4N e/m apparatus, you can see that the positively-charged electrode (the one electrons are attracted to) is labeled "anode." This ...
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1answer
38 views

How often do positrons appear in a typical Wilson cloud chamber?

I would like to know a rough estimate of how often positrons appear per meter cubed per second in a typical Wilson cloud chamber based off of your experience. I'm interested in the same quantity for ...
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1answer
39 views

Why are error bars used instead of error blobs or error rectangles?

In reporting experimental results, it is common to use error bars to communicate uncertainty in measurement of the quantity represented by the y-axis. But, usually, there would also be uncertainty in ...
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25 views

Double slit detector properties

As the only way for me to follow discussions about double slit phenomena is through this site and some videos, I must be clear that I don't know how an actual double slit detector looks like and how ...
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1answer
38 views

How to subtract background from many spectra which were taken with different background intensity?

I have two spectra, a spectrum of background signal (let's call it Reference) and measured spectrum consisting of searched signal and background signal. The searched signal is a peak/s with various ...
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42 views

How can I create gamma rays with energy >2MeV?

I have been exploring pair production (electron/positron) using gamma, and with a Cobalt-60 source this is easy enough. That's just the problem, though. I'm looking for a challenge. I want a stream ...
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2answers
38 views

Errors in measuring devices

I have a question regarding what we mean when we report the error in any measurement. Let's say I have a measuring scale which has markings in mm. Therefore any measurement I make has a limit on the ...
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1answer
46 views

How does a yellow colour filter work in the sense of RGB colour model?

I learnt after reading How do color filters placed in front of a light source,change the color of light that passes through? colour filter work by permitting only one colour and absorbing or ...
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1answer
47 views

What happens when we change the order of colours in Newton disc?

In Newton Disc, different colours constituting the visible region of the electromagnetic spectrum are arranged in the same order as they appear in the spectrum (increasing/decreasing order of ...
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1answer
64 views

Should damping ratio increase or decrease with increase in mass?

I'm currently doing a small project in college for structures being damped. We're adding weights to a structure and measuring the damping affect. We've calculated the damping ratio and coeffecients, ...
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21 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
37 views

Choosing $Z$ particles from a simulator results

I am pretty new to particle Physics. As one of my first projects, I have run a simulation using MadGraph and Delphes. From the simulator result, I am trying to find Z particles produced in the ...
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38 views

Actual data of single photon double slit experiment

I am interested in mapping the actual location of single photon impacts in a double slit experiment as a time series. In other words, I would like three data points for each photon measurement - the ...
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1answer
32 views

Angular Velocity of a point on a deflated tire (gyroscope measurement)

Before I do the experiment, I am a bit confused about the expected signals provided by a 3-axis gyroscope (angular velocities vs. time) mounted on the edge of a (slightly) deflated car tire when the ...