Questions tagged [experimental-physics]

For questions about historical physics experiments, the history of experimental methodology, observations of physical phenomena and related topics.

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How did Stern or Gerlach, of Stern-Gerlach experiment, create individual silver atoms? How were they accelerated?

How, a century ago, could Stern and/or Gerlach KNOW that they had created single silver atoms? How were they moved, or accelerated?
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Signal Processing research: Was matter ever learnt? [closed]

I understand that every energy in our universe can act as a wave or as a mass. If I understand correctly, the scientific and engineeric field of signal processing generally deals with signals from ...
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Was Einstein's "Maschinchen" a predecessor of the photomultiplier tube?

Einstein once got involved in true experimental physics. That is, he designed his little machine (Maschinchen, in German, a word that makes me laugh; Einstein's Maschinchen...) to detect small ...
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114 views

Earliest numeric value for helium D3 line

In late 1868, Norman Lockyer discovered the existence of the D3 emission line of helium in the solar spectrum. What was the earliest published example of a numeric value for the wavelength of this ...
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Did tobacco smoke confound the results of an experiment by entering a reaction with the subject of study?

I dimly remember watching a popular sciencie movie that mentioned an experiment conducted by a pair of great physisicists (Einstein was one of them, unless my memory is playing tricks on me) that had ...
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What can be said about Galileo's tower experiment? Did it take place? [duplicate]

In Wikipedia we can read that Galileo didn't actually performed his tower experiment: According to the story, Galileo discovered through this experiment that the objects fell with the same ...
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Who invented the quadrupole lens for charged particles?

I am wondering who actually invented the (magnetic) quadrupole lens or who used it for the first time. I have found some papers from the 50s and 60s about more complicated systems based on Quadrupoles,...
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70 views

Experimenters regretting throwing away data?

Modern experiments, especially in fields like particle physics, often collect far more data than they can process and save. Similarly, I can imagine that historical experimenters were limited by how ...
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61 views

How did Faraday determine the Faraday's constant?

Here is the reference. I'm wondering how he experimentally proceeded to derive the fact the if we pass 96485 Coulombs through a solution, then 1 gram equivalent of substance is electrolyzed.
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Significance of Higgs model used in Glashow-Salam-Weinberg theory

Sheldon Glashow, Abdus Salam, and Steven Weinberg propose the unification of the weak and electromagnetic interaction between elementary particles. Glashow, Salam, and Weinberg proposed the model ...
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Are there any photographs of the original apparatus used by Hertz to demonstrate the photoelectric effect?

There are many schematics and many photographs of tubes used later but I cannot find a single photograph of the original apparatus. Even the sketches that were made in the late 19th century are ...
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What was known about the properties of the nucleus before the Liquid drop model was proposed?

What was known about the properties of the nucleus (its shape, its density etc) and the nuclear forces before the Liquid drop model was proposed? I believe that some empirical knowledge must be out ...
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How did Millikan consider utilizing oil to help determine the charge of the electron?

Robert Millikan's oil drop experiment help to find the charge of electrons using oil. An x-ray was aimed at the oil drops to give them a charge, and the droplets were attracted to the negative plate. ...
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Was there ever a mathematician or physicist who spearheaded a concerted effort to create a flawless musical instrument?

Specifically, is there any research paper or record of where someone renowned in their field performed experiments by using the properties of physics, engineering or mathematics to develop a musical ...
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1answer
109 views

What was the content of Sakharov's research into cosmic rays?

According to Wikipedia, Sakharov in his early scientific career investigated cosmic rays. It offers no other details. It claims that it was for this work that he was awarded his doctorate. However ...
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259 views

How did Newton prove his third law of motion?

I guess it is an experimental law, so what was the experiment?
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359 views

Did Ptolemy and other Greek scientists actually measure the distance to the Sun?

According to Subhash C. Kak: Early Theories on the Distance to the Sun: “Pancavimsa Brahmana states that the heavens are 1000 earth diameters, de, away from the earth. The sun was also taken to be ...
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80 views

How was it determined that the photoelectric effect is independent of the intensity of light?

How as light intensity measured or determined around 1900? For example, when it was determined that the photoelectric effect was independent of the intensity of the light beam, but rather that it ...
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396 views

Does anyone know of any examples of the Magnus effect in a real battle?

I've read a lot about the Magnus effect altering the trajectories of cannonballs and musketballs. Robins noticed it with Musket balls and Magnus with canonballs, but presumably they weren't the first ...
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What was this experiment tainted by the observer effect?

I once heard a cautionary tale about the dangers of the observer-expectancy effect. It was at least presented as a true example from the history of science, but I'm having trouble identifying the ...
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How did J. J. Thomson establish the particle nature of the electron?

In its article about how the electron was discovered, Wikipedia says that Thomson and his students performed experiments which suggested that cathode rays were negatively charged "particles". But even ...
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224 views

Electric spark discovery

I am searching it on Google but I am not finding,who had discovered static electric spark for the first time,that later Benjamin Franklin proved that this spark(already discovered spark) is same as ...
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How did Henry Cavendish deduce the inverse square law in electrostatics from his experiment in 1772?

An elegant experiment in 1772 by Henry Cavendish. Cavendish charged a spherical conducting shell that contained within it, and temporarily connected to it, a smaller sphere. The outer shell was then ...
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Does Galileo's method of tracing a parabola actually work?

In Two New Sciences, Galileo writes: I take a perfectly round brass ball about the size of a walnut and project it along the surface of a metallic mirror held in a nearly upright position, so that ...
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Hydrogen electrode and its electrode potential

In electrochemistry, all electrode potentials are quoted with reference to the standard hydrogen electrode. Its value is assigned to be 0 volts. I have been searching for the origin of this convention ...
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113 views

Bainbridge's test of mass-energy equivalence

Kenneth Bainbridge was an early pioneer of mass spectroscopy. The Wikipedia article about him says: He used this instrument to verify Albert Einstein's mass-energy equivalence, E = mc2 with a ...
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How did early physicists experimentally assign electronic transitions in atoms?

The spectrum of hydrogen was very well studied by the mid-19th century. However, if one were doing experimental spectroscopy for more complex atoms, one would see plenty of spectral lines in the ...
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What experiments led to the sign of the electron's charge?

The famous Millikan's oil drop experiment in 1908 determined the magnitude of charge of the electron to be 1.59*10^(-19) C. However, it was well known that electron has a negative charge. Although ...
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Who discovered fluid visocity?

Who discovered fluid viscosity and what is the history behind the concept of fluid viscosity? Further, who first defined or parametrized viscosity as shown in Equation 1.1-2 below? Equation 1.1-2 (...
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High voltage / current sources in 19th century cathode ray experiments

In modern chemistry textbooks, a DC source (battery symbol) is usually shown for cathode ray tube experiments by Thomson and others. Certainly, no battery can provide very high voltages needed for gas ...
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454 views

How did the early chemists make a connection between gram formula weight with 1 mole and Avogadro's number?

According to one historian Mustafa Sarikaya's article in Foundations of Chemistry DOI 10.1007/s10698-011-9128-7, the mole concept was introduced to chemistry earlier than Avogadro’s number. The mole ...
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Name of the paper that suffered a famous editor mistake

I have heard about a "famous" mistake made on a physics paper by the editor of a scientific journal but I can't seem to find the paper or even to recall what it was about. Has anyone hear of this and ...
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What is the origin of "normal" in normal coordinates and normal modes?

I am trying to understand why vibrational modes of polyatomic molecules are called "normal" mode of vibrations and with corresponding normal coordinates. What is the origin of the term normal here? I ...
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When was it first noticed, or demonstrated, that radioactive material became warm?

Perusing the Radioactive Thermoelectric Generator or rtg tag in Space SE will show how important these items are for Space exploration both as a source of heat to ...
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How was the idea of observation error introduced?

The first thing a contemporary student of physics learns is the measurement error. As far as I understand, the idea of imprecision was totally foreign to natural philosophers at least until the end of ...
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How did Milikan know that oil drops would acquire only few electron charges?

In the book of Experiment in Modern Physics, by Melissinos, at page 2, it is given that: 2. The Millikan Oil Drop Experiment In 1909, R. Millikan reported a reliable method for measuring ionic ...
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577 views

Whose value of the distance to the Moon did Newton use?

I heard that Newton used the Moon acceleration to come up with his universal law of gravity, but in order to calculate its acceleration you need the distance to the Moon. Whose measurement of this ...
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Who really discovered/invented the Hooke's law?

According to Wikipedia, The law is named after 17th-century British physicist Robert Hooke. He first stated the law in 1676 as a Latin anagram. He published the solution of his anagram in 1678 as: ...
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Could scientists of Newton's time have explored the limits of his laws of motion?

As noted on this Wikipedia page Newton's laws of motion and of gravity were "verified by experiment and observation for over 200 years" and found to be a "good approximation for macroscopic objects ...
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Is this the largest delta precision achieved in any Physics measurement?

Recently I read this article in Phys.org that states: edit: providing previous precision value Over the past few months, physicists have made very rapid progress in bounding the speed of gravity ...
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257 views

Did Aristotle suggest that different kinds of sound might travel at different speeds?

In this answer there is an interesting passage: Also, Aristotle posited that the speed of sound was dependent on frequency. Gassendi had religious/philosophical issues with Aristotle's views, and ...
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History of measuring the mass of the Earth

I am interested in a timeline for the history of measuring the mass of the Earth from the first estimates to the currently accepted value, and in references containing more details.
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Which problems led Newton to three laws of motion?

How did Newton come up with the three laws of motion? Are these laws are true of newton, or they are of Galileo.
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Who is the Westphal behind the Mohr-Westphal specific gravity balance? And how exactly did he improve on Mohr?

I'm a Spanish Physics undergrad, and I was writing a report on an experiment we did on the lab, in which we had to measure a solid's density using the so-called Westphal balance (aka Mohr balance, and ...
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587 views

What did Millikan expect to find when he tried to disprove the photoelectric effect, but proved it instead?

We know that Millikan ended up proving Einstein's photoelectric equation instead of disproving it. Since he aimed at disproving it, what did he have in mind? In other words, what did he expect to see?
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Who first noticed violation of aufbau principle of elements like Cr, Cu, Pd, Au, and how?

It is often referred to as 'anomalous electron configurations' or 'unusual order of filling of orbitals' of a few elements e.g. Cr, Cu, Nb, Mo, Ru, Rh, Pd, Au etc.
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628 views

How was the spontaneous symmetry breaking introduced and how did it lead to the Higgs mechanism?

I'm looking for the way things were connected. It seems me to that it was like this: Spontaneous symmetry breakdown was detected in condensed matter physics. (I'm not sure of facts here) Later it ...
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Which physicist defended the Superconducting Super Collider?

I remember reading a historical overview of particle accelerators, which had a section devoted to the ill-fated Superconducting Super Collider (SSC). The SSC was partially constructed, in the early ...
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What did it historically mean in physics for something to "exist"?

What is the history of influential definitions of objective existence --- This Is Real, It Exists --- in physics? Where did they appear in the literature and in what context were they put forward? ...
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Who first discovered and produced an alternating current?

What physicist first discovered or produced an alternating current and recognized it as such?