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#Electrodynamics

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Daniel Pelliccia

Quite surprisingly, most of the properties of (classical) synchrotron radiation were worked out by G.A. Schott in1907--1912 in his dissertation work.

Working in a 'pre-quantum' world, Schott wanted to explain the observed lines in the emission #spectra of atoms. He started with a ‘Rutherford-like' atomic model where point electrons move in closed orbits around a nucleus: what would the emission spectra of such accelerated particles be like?

Starting from these premises, Schott derived the emission spectrum of (what we know today as) synchrotron light!

As we understand today, the motion of bound electrons cannot be explained by classical #Electrodynamics. Schott's formulas didn't work in describing atomic spectra and his work was forgotten for a while, only to be rediscovered in the 1940s when the first synchrotron machines were being built.

Now, electrons moving on macroscopic curved trajectories are extremely well described by classical electrodynamics, and Schott's formulas work exceedingly well in predicting the properties of #synchrotron light.

#physics

3/N

Continued thread
Daniel Pelliccia

Synchrotron light is conventionally defined as the emission from accelerated ultra-relativistic electric charges.

Ultra-relativistic means that the speed of the charge is extremely close to the speed of light, v ≈ c.

The first part of the book deals with introductory concepts, starting from special relativity, and moving on emission from accelerated charges, then #synchrotron emission from charges in circular and undulating trajectories.

2/N

#Physics#Electrodynamics#books
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The Krononaut Moon Project 🌑

 
Richard Feynman talks about light. 6-min.

❛❛ For his contributions to the development of #quantum #electrodynamics, #Feynman received the #NobelPrize in #Physics in 1965 jointly with Julian Schwinger and Shin'ichirō Tomonaga. ❜❜ #Wikipedia

🔗 youtube.com/watch?v=FjHJ7FmV0M 2007 Nov 02
🔗 Wikipedia.org/wiki/Richard_Fey … #RichardFeynman
🔗 Wikipedia.org/wiki/Light … #Light

YouTubeRichard Feynman talks about lightBy sdfhsfh
#Community#TimeTravel#Research
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Queen Calyo Delphi

Current transformers and current clamp probes are an ingenious way to measure the current in a wire without affecting the circuit being measured. The measurement technique exploits the complementary phenomena that a current induces an orthogonal magnetic field that curls around the current, and a magnetic flux induces an orthogonal current flow that curls around the flux.

Here's a doodlesketch to illustrate the phenomenon:

#physics#electricity#electrodynamics
Forgetful Bri :ms_robot_grin:

Possible idea for the #Flatland simulator: given a point charge, it might be possible to accurately measure the electric field at another point with the following process:
- Draw a line segment connecting the two points.
- If no shapes intersect that segment, or if the interior regions of all intersecting shapes have the same permittivity as free space, then just use Coulomb's Law.
- Otherwise, recursively apply Coulomb's Law along the entire line, using different permittivity values as needed.

Kind of a #DrawTheRestOfTheDamnOwl of a description, but I need sleep. Hoping this will still make sense later.

Pros of this approach:
- The electric field system wouldn't need to be overhauled.
- It would continue functioning in a continuous coordinate space.

Cons of this approach:
- O(n^2) computational complexity will catch up to me eventually. At that point, I'll wish I'd gone for the gridded (and sub-quadratic?) approach.
- I don't know if it's actually physically sound.

#electrostatics#electrodynamics#electromagneticfields
Antonio Ganfornina Andrades

Acaba de subirse a arXiv nuestro último manuscrito sobre la amplificación del vacío cuántico en materiales cuyas propiedades ópticas cambian en el tiempo siguiendo perfiles arbitrarios.

Our latest manuscript, Quantum vacuum amplification in time-varying media with arbitrary temporal profiles, has just been uploaded to arXiv.

arxiv.org/abs/2312.13315

arXiv.orgQuantum vacuum amplification in time-varying media with arbitrary temporal profilesIn this work we address quantum vacuum amplification effects in time-varying media with an arbitrary time-modulation profile. To this end, we propose a theoretical formalism based on the concept of conjugated harmonic oscillators, evaluating the impact on the transition time in temporal boundaries, shedding light into the practical requirements to observe quantum effects at them. In addition, we find nontrivial effects in pulsed-modulations, where the swiftest and strongest modulation does not lead to the highest photon production. Thus, our results provide key insights for the design of temporal modulation sequences to enhance quantum phenomena.
#quantumoptics#metamaterials#Electrodynamics
j_bertolotti

#PhysicsFactlet:
Signals (e.g. light) move at a finite speed, so there is a time lag between when they are emitted and when they are detected. If the source is moving, the detector will "see" the signal that was emitted at a previous time, not the signal that is being emitted right now, and this time lag can change with time in a complicated way.
(Notice that, as the source is always moving slower than the signal, the detector sees the signals in the same order they were emitted.)
#Physics #ITeachPhysics #Electrodynamics #Optics #Relativity

Project Gutenberg

Wilhelm Eduard Weber died #OTD in 1891.

He was a German physicist and, together with Carl Friedrich Gauss, inventor of the first electromagnetic telegraph, which connected the observatory with the institute for physics in Göttingen.

The first usage of the letter "c" to denote the speed of light was in an 1856 paper by Kohlrausch and Weber (Elektrodynamische Maassbestimmungen). The SI unit of magnetic flux, the weber (symbol: Wb) is named after him. via @Wikipedia

#science#electrodynamics
j_bertolotti

Short story time:
When I was doing my PhD, we had in the lab an old Argon laser (which we used to pump a Ti:Sapphire, for those familiar with lasers). If you have never seen one, Argon lasers are massive, can output a ton of power, and eat a crazy amount of current, so much that the laser had its own dedicated industrial pentaphase plug.
I don't remember how many Amperes of current flew in those cables. What I remember is that, when you turned on the switch in the morning, the change in current (from zero to whatever the steady state value was) was enough to make the cable shake.
This happens because the electromagnetic field inside and around the cable stores momentum, and so it kicked the cable when building up.
I am not sure that laser still exists, and I have never been able to find a video of a cable shaking when the current is switched on, but it would be great to have such a video when teaching electrodynamics (and in particular how momentum and angular momentum can be stored in an electromagnetic field).
#ITeachPhysics #Physics #Electrodynamics #Laser

Tiago Peixoto

Crosspost from @ZierlerDavid@twitter.com:

David Griffiths of @Reed_College_@twitter.com remembers growing up in college towns, mass-less field theory @harvardphysics@twitter.com, the November Revolution @SLACLab@twitter.com, the singularity of Sidney Coleman's lectures, and the dynamism of #electrodynamics in historical perspective

aip.org/history-programs/niels

🐦🔗: twitter.com/ZierlerDavid/statu

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