Propagating solutions to Maxwell’s equations in classical electromagnetism and real photons in quantum electrodynamics. A superset of thermal-radiation.

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Does the mediation of electric or magnetic force require distinct electron orbitals?

In the case of ordinary photons of light, matter interacts with light via electrons that orbit the nucleus. If the specific energy of a photon E = hv can be found in the atom as the energy difference ...
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5answers
124 views

Can a Coronal Mass Ejection (CME) cause a blackout on Earth and why?

Can a Coronal Mass Ejection (CME) cause a blackout on Earth and why is it so what's the relation between electro magnetic radiations and electrical and electronic appliance.what exactly does it do to ...
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1answer
190 views

Is it possible to “focus” a radio wave to target an area much smaller than its wavelength?

Recently I was reading about a technology that uses radio waves to stimulate neurons to fire. The radio waves have the advantage of being able to pass through the skull (hence being non-invasive) but ...
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1answer
94 views

Electromagnetic waves in vacuum

If there is no source then also there is electromagnetic waves described by Maxwell equation. how if there is no source then existence of EM waves. What gives energy to this EM waves. Is it vacuum ...
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1answer
760 views

Effect of varying distance of light source from a Light Dependant Resistor

I'm doing the experiment described here and I have a few questions about it. I have a miniature light dependent resistor (LDR) hooked to a multimeter set to $\Omega $ and a $25\,\mathrm W$ Light ...
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6answers
3k views

Is a suit that hides a soldier's heat signature fundamentally possible?

I recently played "Crysis", a game where the protagonist wears a suit that allows the player to hide both himself and his heat signature. Then I watched Iron Man 3, where a kid suggests that Tony ...
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1answer
85 views

Rayleigh-Jeans Law difference between the frequency and wavelength forms [duplicate]

I don't understand the conversion between the frequency and wavelength forms of the Rayleigh-Jeans equation for spectral radiance. According to the Wikipedia article on the Rayleigh-Jeans law: ...
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1answer
66 views

What is going on in a rotating magnet in a quantum scale?

If there is a rotating magnet in an empty space and there is no outer field acting on it. Rotating in such a way that after half rotation magnet's N pole will be in the place where magnet's S pole ...
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1answer
750 views

Faraday rotation effect in circularly polarized waves?

We all know farady effect is observed in linearly polarized wave when it passes through a dielectric medium and magnetic field is along the direction of propagation. Is this phenomenon observable in ...
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2answers
162 views

Are solutions coordinate invariant?

In the case of electromagnetism, we can solve the sorceless wave equation in Cartesian coordinates ($x$,$y$,$z$) getting plane waves as solutions: $$ u(x) = A(x-ct) + B(x+ct) $$ and actually I am not ...
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2answers
3k views

Why does noise affect FM radio less than AM?

Frequency modulated waves are less susceptible to noise compared to amplitude modulated signal. This is because the information in an FM signal is transmitted through varying the frequency, and not ...
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1answer
33 views

Can a phase array evoke a standing wave at a focal point that has a much higher frequency that the constituent emitted frequencies?

This is a phased array: How can you focus sound? It can focus many waves of weak radio wave or light into a single focal point that's very strong. Now imagine that we delay half of the emitters by ...
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2answers
75 views

How can the thrust due to radiation pressure be amplified in photonic laser thruster?

The thrust is amplified due to repeated bouncing of photons between two mirrors as shown in the diagram in this: Why does repeated bouncing of photons produce amplified thrust when the answer in ...
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0answers
37 views

Is it possible to create arbitrary shapes of magnetic fields?

I've been reading about Transcranial Magnetic Stimulation (TMS) which can activate neurons using a magnetic field, which got me thinking... what if we can pick and choose exactly which neurons to ...
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0answers
77 views

Hydrogen 2p3/2 -> 1s1/2 transition polarisation and angular distribution

Could you please help me. I have to calculate the intensity angular and polarisation distribution in hydrogen electric dipole transition $\text{2p}_{3/2}\rightarrow \text{1s}_{1/2}$. To do this I ...
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1answer
114 views

Is this even possible to understand this proof? [closed]

Can someone explain what kind of sorcellery is this proof about Maxwell's equations: http://proofs.wiki/Maxwell%27s_equations_predict_that_the_speed_of_light_is_constant. Is this a joke?
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1answer
38 views

Is there any difference in radiation pressure for two observers in different gravitational potential?

Suppose that a light beam is shone upwards from surface of a planet. So, due to gravitational redshift, the frequency of the light perceived by observer far from the surface will be lower than that ...
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3answers
1k views

Reconciling refraction with particle theory and wave theory

I have searched the web for good answers to why refraction occurs when light moves from one medium to another with different density. I have limited background in physics and want to know if there is ...
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3answers
230 views

Which electromagnetic radiation is faster in water, microwaves or light?

Well I've been asked this question, but I haven't been able to come with an answer yet using books and some web searches. The point is as the title says, to answer the question with the whole ...
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2answers
2k views

What is the effect of polarization on diffraction by a narrow slit?

Consider the well known demonstration of diffraction by a narrowing slit. (See for example the demonstration at the 30 minute mark of this lecture at MIT by Walter Lewin) It is my (possibly mistaken) ...
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2answers
85 views

Sun: When its closest and when its farther away?

If the sun is closest to the North American Hemisphere in the winter than it is in the summer, why doesn't our faces and hands tan and/or blister quicker? Please provide two hyperlink sources with ...
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2answers
235 views

Why is the Luminiferous aether theory wrong? [closed]

I saw on this page about the constant speed of light that there are two ways of interpreting this constant speed: General relativity The Luminiferous aether theory I understand why the theory of ...
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1answer
31 views

Wave guide boundary conditions

Why only the normal component of Electric field and the parallel component of Magnetic field exist at the surface of a wave guide or any conductor?
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0answers
30 views

Where does the factor of $\gamma^2$ come from in synchrotron radiation?

I've read the derivation for synchrotron radiation (as derived by Griffiths), so I know how to get it given the retarded potentials, etc. I'm having a hard time with intuition. The derivation in ...
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0answers
59 views

The energy of an electron in a time-dependent electric field

Is energy of an electron in a time-dependent electric field any different from the one in a static field? Why did D.Griffith state in his "Intro to QM"( when he discussed the perturbation of EM waves ...
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1answer
68 views

Electromagnetic radiation bending on Earth

Most articles say that a radiowave is able to propagate itself beyond the horizon because it is reflected off by the ionosphere (and the Earth itself). But do radio waves also get bent according to ...
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2answers
94 views

Solution of one dimensional wave equation by variable separation method

When solving the One dimensional wave equation by variable separable method, we equate left-hand side and right-hand side to a constant which is negative in nature. Why has the constant be only ...
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2answers
90 views

Does a rotating DC motor near a TV affects the signals coming in the TV?

In my TV cable the signals were quite noisy so i cut the wire and hanged both the wire parallel to each other. Then the signals became very clear and everything was going alright. Once I was ...
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1answer
151 views

Non-polarised light

We know the beam of light oscillates in electric field and magnetic field, both perpendicular to both the wave of propagation and each other. What does, however, a non-polarised beam of light look ...
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2answers
37 views

How are different wavelength components collected by the same detector in a spectrometer?

Let's think, we have a detector array (128x1 and each CMOS detector responds 400 to 1000 nm TSL1401CL that way, each detector has 4.6875 nm interval). Then, basically in a spectrometer a prism reflect ...
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3answers
134 views

Plane waves - EM wave

An accelerating electric charge will emit transverse electromagnetic waves. These waves are propagating away in wave fronts that become flatter and flatter as getting further from the source. So they ...
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1answer
71 views

Does reflected light change LED power consumption?

If I enclose an LED in "tin foil" so that the photons it gives off are reflected back to it, would the power consumed by the LED go down?
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3answers
91 views

Negative frequency contributions for very short pulses?

I am wondering if very short optical light pulses can have a Gaussian envelope? When I describe the pulse shape with a Gaussian than the frequency distribution has also a Gaussian shape. But if the ...
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1answer
55 views

Subtraction In Quadrature?

I have a system of particles (electrons) with an initial RMS energy spread (say "1"). It goes through a section of constant magnetic field (bend magnet) and the electrons radiate. The electrons lose ...
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2answers
170 views

Why don't X-rays travel through water?

Why don't X-rays travel through water? I read that X-Rays don't travel through water, but what is the main reason? See this link:http://henke.lbl.gov/optical_constants/ it shows X-ray transmission ...
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4answers
170 views

Why Light isn't like an Acoustic wave?

I just wanted to know why light isn't an Acoustic wave.Is it because light wave doesn't obey acoustic properties?
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2answers
3k views

How do microwaves heat moisture-free items?

Today I learnt that microwaves heat food by blasting electromagnetic waves through the water molecules found in the food. Does that mean food with 0% moisture (if such a thing exists - dried spices?) ...
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3answers
899 views

What is meant by the temperature of the CMB?

This is what I commonly read: The CMB came to existence when atoms where formed and photons weren't constantly absorbed anymore. In other words, the universe became "transparent". Because of the ...
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2answers
3k views

Wavelength dependent refractive index

I read in a book about optical fibers that the different spectral components of a light pulse transmitted in the fiber propagate with different velocities due to a wavelength dependent refractive ...
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2answers
64 views

Do I need to convert units to be compatible with constants?

I want to calculate the wavelength of radiation given its energy. I know I need to use $E=h f$ and $f = c / \lambda$. All I'm given is $E = 20 \text{ keV}$, now my true question is: Do I use $E = ...
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1answer
100 views

Electromagnetic interaction physical interpretation [duplicate]

Why do radio waves, X-ray and gamma rays penetrate through matter? Can anyone explain me this in terms of incident energy or wavelength of the photon and the effective cross-section that these photons ...
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1answer
130 views

Stimulated emission direction

Place a sub-micron clump of crystal violet molecules in front of a multipixel detector. Raise the molecules to an electronically excited state with a beam of 590 nm light, illuminating from the side ...
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3answers
741 views

Electromagnetic waves should stop while encountering a conducting shell?

I am a high school student who has just started reading elementary electromagnetism and am a completely beginner in this subject. I have read in books that EM waves are nothing but sinusoidal ...
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4answers
5k views

Why do prisms work (why is refraction frequency dependent)?

It is well known that a prism can "split light" by separating different frequencies of light: Many sources state that the reason this happens is that the index of refraction is different for ...
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3answers
783 views

Does light change phase on refraction?

I have seen a lot about when light undergoes a phase change when it is reflected. But does it undergo a phase change when refracted and if so why and if not why not?
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1answer
3k views

Does the absence of a sound particle indicate that there are no photons?

Sound is usually referred to as just "sound waves" - we do not talk about a "sound particle" and only as a wave or "matter wave." Could something similar apply to light i.e. that there really is no ...
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4answers
2k views

Can radio waves be formed into a pencil beam?

Laser beams are said to have high "spatial coherence". This means that the beam is highly concentrated even at long distances (low spread). Can this be achieved with radio waves (much longer waves) ...
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2answers
2k views

Does infrared rays pass through polarized glass?

Actually I had asked in another post that "Does infrared rays pass through active shutter glass" but someone just commented that infrared rays dont pass through polarized glass. If infrared rays ...
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1answer
69 views

Why is $B=\frac{1}{\omega} k\times E$?

Why can we derrive from $B=\frac{k}{\omega}|E|$ the formula $B=\frac{1}{\omega} k\times E$ ? Obviously, because they are perpendicular, but why is it mathematically legitimate?
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Is the de Broglie wavelength of a photon equal to the EM wavelength of the radiation?

Is the de Broglie (matter) wavelength $\lambda=\frac{h}{p}$ of a photon equal to the electromagnetic wavelength of the radiation? I guess yes, but how come that photons have both a matter wave and an ...