#electrodynamics — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #electrodynamics, aggregated by home.social.
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Reading the dissertation was fascinating because it reveals a side of #Helmholtz that is rarely discussed today. Long before his work on #EnergyConservation, #electrodynamics, and #WavePhysics, he was already deeply engaged with #anatomical and #biological questions.
It also shows that some core ideas about the comparative structure of nervous systems were already being articulated in the early 19th century.
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Reading the dissertation was fascinating because it reveals a side of #Helmholtz that is rarely discussed today. Long before his work on #EnergyConservation, #electrodynamics, and #WavePhysics, he was already deeply engaged with #anatomical and #biological questions.
It also shows that some core ideas about the comparative structure of nervous systems were already being articulated in the early 19th century.
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Reading the dissertation was fascinating because it reveals a side of #Helmholtz that is rarely discussed today. Long before his work on #EnergyConservation, #electrodynamics, and #WavePhysics, he was already deeply engaged with #anatomical and #biological questions.
It also shows that some core ideas about the comparative structure of nervous systems were already being articulated in the early 19th century.
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Reading the dissertation was fascinating because it reveals a side of #Helmholtz that is rarely discussed today. Long before his work on #EnergyConservation, #electrodynamics, and #WavePhysics, he was already deeply engaged with #anatomical and #biological questions.
It also shows that some core ideas about the comparative structure of nervous systems were already being articulated in the early 19th century.
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Reading the dissertation was fascinating because it reveals a side of #Helmholtz that is rarely discussed today. Long before his work on #EnergyConservation, #electrodynamics, and #WavePhysics, he was already deeply engaged with #anatomical and #biological questions.
It also shows that some core ideas about the comparative structure of nervous systems were already being articulated in the early 19th century.
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I got a little long, but here is my full derivation of why a hydrogen atom is not like a tiny solar system. #physics #electrodynamics
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Here's a #python animation I made for #electrodynamics
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New #electrodynamics #physics video - looking at reflection and transmission of electromagnetic waves. Snell's law and Brewster's angle.
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#PhysicsFactlet
Scattering VS Extinction
In #Optics, the concepts of scattering and extinction are closely related. So closely related that many people tend to confuse them.
Imagine to illuminate a small object with a beam of light. If the object is small the scattered field will be essentially a spherical wave, and the total field will be the incident one plus the scattered field.
If we were able to measure directly the field (as we can do in the microwave regime) we could happily stop here, but in optics we can only measure intensities, and the intensity is defined as the time average of the modulus of the Pointing vector. In most cases of interest, the modulus of the Poynting vector is proportional to the modulus squared of the electric field (which explains why we often that a shortcut and just talk about |E|²).
So the quantity we measure is proportional to |Eᵢₙ +Eₛ|², which is the sum of the Poynting vector of the incident field, the Poynting vector of the scattered field, plus the cross terms. These cross terms are what we usually call "extinction" and are the result of the interference between the incident and scattering fields(and the reason why you get a "shadow" behind the scatterer). -
#PhysicsFactlet
Scattering VS Extinction
In #Optics, the concepts of scattering and extinction are closely related. So closely related that many people tend to confuse them.
Imagine to illuminate a small object with a beam of light. If the object is small the scattered field will be essentially a spherical wave, and the total field will be the incident one plus the scattered field.
If we were able to measure directly the field (as we can do in the microwave regime) we could happily stop here, but in optics we can only measure intensities, and the intensity is defined as the time average of the modulus of the Pointing vector. In most cases of interest, the modulus of the Poynting vector is proportional to the modulus squared of the electric field (which explains why we often that a shortcut and just talk about |E|²).
So the quantity we measure is proportional to |Eᵢₙ +Eₛ|², which is the sum of the Poynting vector of the incident field, the Poynting vector of the scattered field, plus the cross terms. These cross terms are what we usually call "extinction" and are the result of the interference between the incident and scattering fields(and the reason why you get a "shadow" behind the scatterer). -
#PhysicsFactlet
Scattering VS Extinction
In #Optics, the concepts of scattering and extinction are closely related. So closely related that many people tend to confuse them.
Imagine to illuminate a small object with a beam of light. If the object is small the scattered field will be essentially a spherical wave, and the total field will be the incident one plus the scattered field.
If we were able to measure directly the field (as we can do in the microwave regime) we could happily stop here, but in optics we can only measure intensities, and the intensity is defined as the time average of the modulus of the Pointing vector. In most cases of interest, the modulus of the Poynting vector is proportional to the modulus squared of the electric field (which explains why we often that a shortcut and just talk about |E|²).
So the quantity we measure is proportional to |Eᵢₙ +Eₛ|², which is the sum of the Poynting vector of the incident field, the Poynting vector of the scattered field, plus the cross terms. These cross terms are what we usually call "extinction" and are the result of the interference between the incident and scattering fields(and the reason why you get a "shadow" behind the scatterer). -
#PhysicsFactlet
Scattering VS Extinction
In #Optics, the concepts of scattering and extinction are closely related. So closely related that many people tend to confuse them.
Imagine to illuminate a small object with a beam of light. If the object is small the scattered field will be essentially a spherical wave, and the total field will be the incident one plus the scattered field.
If we were able to measure directly the field (as we can do in the microwave regime) we could happily stop here, but in optics we can only measure intensities, and the intensity is defined as the time average of the modulus of the Pointing vector. In most cases of interest, the modulus of the Poynting vector is proportional to the modulus squared of the electric field (which explains why we often that a shortcut and just talk about |E|²).
So the quantity we measure is proportional to |Eᵢₙ +Eₛ|², which is the sum of the Poynting vector of the incident field, the Poynting vector of the scattered field, plus the cross terms. These cross terms are what we usually call "extinction" and are the result of the interference between the incident and scattering fields(and the reason why you get a "shadow" behind the scatterer). -
#PhysicsFactlet
Scattering VS Extinction
In #Optics, the concepts of scattering and extinction are closely related. So closely related that many people tend to confuse them.
Imagine to illuminate a small object with a beam of light. If the object is small the scattered field will be essentially a spherical wave, and the total field will be the incident one plus the scattered field.
If we were able to measure directly the field (as we can do in the microwave regime) we could happily stop here, but in optics we can only measure intensities, and the intensity is defined as the time average of the modulus of the Pointing vector. In most cases of interest, the modulus of the Poynting vector is proportional to the modulus squared of the electric field (which explains why we often that a shortcut and just talk about |E|²).
So the quantity we measure is proportional to |Eᵢₙ +Eₛ|², which is the sum of the Poynting vector of the incident field, the Poynting vector of the scattered field, plus the cross terms. These cross terms are what we usually call "extinction" and are the result of the interference between the incident and scattering fields(and the reason why you get a "shadow" behind the scatterer). -
Here is my lecture on EM plane waves for #electrodynamics #physics. Yes, I include a #python model for a plane wave
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Here is circularly polarized wave - from #electrodynamics #physics using #python
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#paperOfTheDay "On the identification of gravitation with a massless spin 2 field" from 1986. This article deals with the general theory of #relativity . Namely, if one starts from a generic field theory of a spin-2 particle, the resulting theory has a symmetry that suggests to identify it with general relativity. However, if one stays as closely as possible analogous to #electrodynamics and the conventional assumptions of field theory (fields decay at infinity), then the only possibility seems to be that the universe is asymptotically flat an has no holes or any other topological features, and the cosmological constant must be zero.
I am not sufficiently familiar with general relativity to assess if this is in fact the only possible conclusion. In any case, the paper is a nice exposition of field theory with spin 2, a topic which is not usually covered in introductory physics lectures.
https://link.springer.com/article/10.1007/BF03053785 -
This is an interesting paper examining the transmission of DC current as ω→0 in the telegrapher's equation using the Heaviside step function.
Abstract—We explore the question of how direct current (DC) power is transmitted by electromagnetic fields in TEM/Quasi-TEM structures despite the static curl laws ∇ × E = 0 and ∇ × H = J. In this work we treat DC as the long-time limit of a causal step excitation.
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I think this #physics #python video turned out better than I expected. Verifying Faraday's Law for #electrodynamics
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New #physics #python #electrodynamics post. Deeper dive into Faraday's law - using the changing magnetic vector potential to calculate the electric field to show emf = -dPhi/dt
https://rjallain.medium.com/the-boom-moment-using-python-to-show-faradays-law-always-works-2f79e5941cf0?sk=c0a11665abb669f1671ac91a762c9119 -
New #physics #electrodynamics video. Calculating the force and torque on a loop of current near a bar magnet. Of course I do this two ways - first by treating the loop as a bunch of tiny wires and second using m x B and del(m dot B). #python
https://youtu.be/GqPPqCDN7go -
New #physics video - magnetic vector potential. I think making a 3D visual with #python really helps. #electrodynamics
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Here's my #physics explanation of calculating the magnetic field due to a line, a loop, and a solenoid. Oh, of course #python is included. #electrodynamics
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New #physics #electrodynamics video - finding the magnetic field due a solenoid 3 ways: Ampere's law, Biot-Savart and #python (of course).
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New #physics #python video - visualizing the magnetic field due to a loop of current. Bonus: calculating the magnetic dipole moment for #electrodynamics
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New #physics video - finding the magnetic field due to a loop of current. No tricks in this derivation - but I do it again with #python (you probably knew that). #electrodynamics
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New #physics post - does Gauss's Law still work with dielectrics? This is basically a summary of the electric displacement field. #electrodynamics
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New #physics #electrodynamics video - using #python to display the electric field due to dipole water molecule.
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New #physics #electrodynamics video - 2 different ways to find the electric field from the dipole moment.
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New #physics #electrodynamics video - finding the electric potential and electric field due to a dipole. #iteachphysics
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New #physics #electrodynamics #python video - AGAIN doing the finite difference calculation of electric potential, but this time with Jupyter notebooks. Bonus: calculating the electric field. #iteachphysics
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New #physics #electrodynamics video - solving 2d electric potential with python and a finite difference relaxation method. #iteachphysics
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New #physics video (this one is long). Using separation of variables to find the electric potential in a 2D area with boundary conditions ( #electrodynamics). Yes, 3D surface plot included at the end.
https://youtu.be/M3RDynwsFuw -
New #physics #python #electrodynamics video - showing that we can repeat the method of images for a charge near a plate with a many body problem.
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New #physics #python video - visualizing the electric flux through a cube. This is for my #electrodynamics course #iteachphysics
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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.
3/N
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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
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#quantummechanics #quantum #einstein #quotes #spacetime #spacecraft #scientist #spacex #e #schroedinger #elonmusk #physics #electrodynamics #biology #blackhole #chemistry #quantumphysicist #quantumdeviations #spiritualmentor #energyhealer #quantumbiology #energyofyou rumble.com/v6tkc4h-essa...
Essay - Nichiren Shoshu True B... -
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
🔗 https://www.youtube.com/watch?v=FjHJ7FmV0M4 2007 Nov 02
🔗 https://Wikipedia.org/wiki/Richard_Feynman … #RichardFeynman
🔗 https://Wikipedia.org/wiki/Light … #Light -
In 1917, Albert Einstein established the theoretical possibility of masers and lasers. #Poetry #Science #History #Electrodynamics #Lasers #Masers #Einstein (https://sharpgiving.com/thebookofscience/items/p1917.html)
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In 1912, Reginald Fessenden demonstrated the first successful sonar. #Poetry #Science #History #Electrodynamics #Sonar #Fessenden (https://sharpgiving.com/thebookofscience/items/p1912b.html)
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@ekmiller Oh My Various Goddess Abstractions. This is so incredibly beautiful 😍
STDP reveals that timing reshapes connections.
This paper reveals how, and it's... musical.The brain as an "instrument" takes on new meaning.
https://bcs.mit.edu/news/brain-networks-encoding-memory-come-together-electric-fields-study-finds
#neuroscience #neurobuzz #cogsci #neurons #music #electricity #energy #fieldtheory #electrodynamics #instrument
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@ekmiller Oh My Various Goddess Abstractions. This is so incredibly beautiful 😍
STDP reveals that timing reshapes connections.
This paper reveals how, and it's... musical.The brain as an "instrument" takes on new meaning.
https://bcs.mit.edu/news/brain-networks-encoding-memory-come-together-electric-fields-study-finds
#neuroscience #neurobuzz #cogsci #neurons #music #electricity #energy #fieldtheory #electrodynamics #instrument
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@ekmiller Oh My Various Goddess Abstractions. This is so incredibly beautiful 😍
STDP reveals that timing reshapes connections.
This paper reveals how, and it's... musical.The brain as an "instrument" takes on new meaning.
https://bcs.mit.edu/news/brain-networks-encoding-memory-come-together-electric-fields-study-finds
#neuroscience #neurobuzz #cogsci #neurons #music #electricity #energy #fieldtheory #electrodynamics #instrument
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@ekmiller Oh My Various Goddess Abstractions. This is so incredibly beautiful 😍
STDP reveals that timing reshapes connections.
This paper reveals how, and it's... musical.The brain as an "instrument" takes on new meaning.
https://bcs.mit.edu/news/brain-networks-encoding-memory-come-together-electric-fields-study-finds
#neuroscience #neurobuzz #cogsci #neurons #music #electricity #energy #fieldtheory #electrodynamics #instrument
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@ekmiller Oh My Various Goddess Abstractions. This is so incredibly beautiful 😍
STDP reveals that timing reshapes connections.
This paper reveals how, and it's... musical.The brain as an "instrument" takes on new meaning.
https://bcs.mit.edu/news/brain-networks-encoding-memory-come-together-electric-fields-study-finds
#neuroscience #neurobuzz #cogsci #neurons #music #electricity #energy #fieldtheory #electrodynamics #instrument
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#ArvinAsh - Why Does #Light Exist? What is Its #Purpose?
https://www.youtube.com/watch?v=uT-6YVrecro&ab_channel=ArvinAsh
#PhilosophyOfScience #PhilosophyOfPhysics #Optics #ElectromagneticSpectrum #ElectromagneticWaves #Electromagnetism #Physics #QuantumPhysics #QuantumMechanics #QM #Senses #Sight #Photon #Photons #Duality #Einstein #AlbertEinstein #SpecialRelativity #Electrodynamics #QuantumElectrodynamics #QED
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#PhysicsFactlet
If you put a dipole close to a mirror it is easy to see that its emission pattern is modified due to interference. A bit less easy to see (and thus less known) is the fact that also the total emitted power depends on the distance from the mirror, as at certain distances a significant fraction of the reflected wave goes back on the dipole in antiphase with the emission, thus reducing the emitted power.
#Physics #ElectroDynamics #Optics #LDOS #Visualization