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

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38 views

How is the virtual image reconstructed from a hologram?

To make a hologram a film is exposed to an incident plane wave and wave from the object to record the interference pattern on the film. The principle is commonly explained in a way like that in p.1212 ...
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27 views

What is ultimate AC frequency and phenomena related to it?

Just as in title. What is the top AC frequency physically possible to obtain? And are there (and if yes, what?) phenomena occuring only at large frequencies? I'm thinking about a metallic wire. I know ...
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60 views

What's the meaning of linear medium in electromagnetism?

I'm studying the book Polarimetric Radar Imaging: From Basics To Applications and on page 31, there's this sentence: In the following, we shall consider the propagation of an electromagnetic ...
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2answers
43 views

Why array of telescope is used?

To increase the resolution of an instrument, smaller wavelength and larger aperture is desirable. It is mentioned in some textbooks that the "effective" diameter of a telescope can be increased by ...
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14 views

Question about dark fringe in diffraction

In finding the angle for the mth dark fringe of single slit diffraction using Huygen's principle, they usually split the slit into equal portions. For example, to find the first dark fringe the slit ...
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2answers
54 views

If heat can't be transformed into other forms of entropy, why do hot things radiate electromagnetic waves?

The laws of entropy says entropy can only increase. On the other hand, if I take a hot object, it will naturally convert its heat into EM radiation. How is this possible? Does EM radiation count as ...
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13 views

Does resonant inductive coupling work in the presence of a strong magnetic field?

Does resonant inductive coupling work in the presence of a strong magnetic field? I am unsure because resonant inductive coupling uses magnetic fields to transmit power wirelessly and a strong ...
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1answer
142 views

Why is the wave equation so pervasive?

The homogenous wave equation can be expressed in covariant form as $$ \Box^2 \varphi = 0 $$ where $\Box^2$ is the D'Alembert operator and $\varphi$ is some physical field. The acoustic wave ...
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19 views

Should I observe single/double escape peaks for all energies above 1022 keV

I have already asked a question similar to this, but that question was specifically relating to the case of K-40. I'm going to generalize it to any case My question is to do with the field of gamma ...
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3answers
58 views

Observing a photon during flight

When I was reading about the double-slit experiment in quantum mechanics, everything seems to make sense in terms of the waves and the interference pattern, but if thinking more about this ...
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21 views

Do x-rays show single slit diffraction patterns? [closed]

Do x-rays show single slit diffraction?If yes/no please explain.
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1answer
58 views

What's really a radiowave

Can you explain what we interpret as an EM wave? In radio communications, a radio receiver is an electronic device that receives radio waves and converts the information carried by them to a ...
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32 views

Reflection of EM waves

In reflection of e m waves at the boundary, to show the reflected magnetic fields we put negative sign in the unit vector, example, if the B is along z direction we put (-k) in he reflected wave, ...
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70 views

Physical meaning of wavelength of an EM wave

What is the physical meaning of the wavelength of light? This question has been asked before but I cannot find a satisfactory answer. Some respondents have said that the question is vague, I don't ...
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How many X-rays does a light bulb emit?

I read somewhere that most things1 emits all kinds of radiation, just very few of some kinds. So that made me wondering whether there is a formula to calculate how many X-rays an 100W incandescent ...
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1answer
70 views

Is the photon's wave function the same as an electromagnetic wave(light)? [duplicate]

The first that i have been taught in Quantum Mechanics is the photoelectric phenomenon. Without analyzing it, it concludes that when we shine light at the circuit(roughly speaking), the work required ...
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1answer
83 views

An object glows red at around 1000K while a red star is around 3000K. What causes this misalignment in spectra?

According to the H-R diagram, a red star is 3000K, a yellow star is 6000K and a white star 10000K. But a hot metal appears red at 1000K, yellow at 1500K and white at 2000K.(approximately) Why is ...
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2answers
78 views

Electromagnetic wave and quantum mechanics [duplicate]

I'm very new to physics. I studied and read about quantum mechanics and what the assumptions are (wave particle duality, uncertainty principle, observation, wave function collapse, etc.), but I also ...
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1answer
47 views

Why does friction produce heat?

What causes two objects sliding against each other to produce heat? Why don't they generate visible light or something else?
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64 views

Can I produce radio waves by waving my hand?

I learned that EM waves are caused by the movement of charges (e.g. electrons), because they have an electric field and the change in the particle's position doesn't update the field instantly all ...
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3answers
114 views

Why photons reflect off glass?

Why photon reflects and refracts through glass? Some photons pass through glass and some reflects.I know this is due to energy levels of electrons of glass, an incoming photon is unable to excite the ...
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2answers
99 views

What is the amplitude of a (EM) wave?

Amplitude is: Peak-to-peak amplitude is the change between peak (highest amplitude value) and trough (lowest amplitude value, which can be negative). With appropriate circuitry, peak-to-peak ...
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3answers
84 views

What is an EM wave? [closed]

How does an EM wave carry energy? What is an EM wave? (Is it a collection of photons?) What are the mechanics behind it? I am an engineer and I've been taught to think of light (light is my area ...
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1answer
55 views

Question about lens maker's formula

I am trying to follow the derivation of lens maker's formula from the textbook "University Physics", p.1133 ...
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1answer
72 views

Can photons accelerate? [duplicate]

I was just wondering if there's a (hypothetical) situation where a photon could accelerate and what the consequences of this might be?
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1answer
22 views

Transmission of light, sub-wavelength apertures, and cut-off frequencies

I was hoping someone could please explain how the transmission of light through a sub-wavelength aperture in a metal film, at a particular wavelength, changes when the aperture is: i) above cut-off ...
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2answers
50 views

Why conductors don't scatter light?

Air molecules can be oscillated by E field and re-radiate EM waves in different directions. However, if light is shined to a conductor the E field oscillate the free charges but the effect is to ...
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2answers
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Will neutral particles be affected by EM waves?

Air molecules scatter sunlight and makes the sky blue. Many books say that the air molecules are oscillated by E field and so they become sources of EM waves. Is it because the air molecules have ...
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70 views

How do EM waves travel in a vacuum? [duplicate]

Apart from that electric and magnetic field variation thing, is there any other explanation? Can photons simply pass through vacuum?
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49 views

Will I sunburn faster when driving compared to being parked?

I'm not sure if the same logic applies to light and rain when comparing running/driving with a stagnant situation. See, e.g. Why does driving faster make my windshield catch more rain? Suppose I have ...
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17 views

Polarized light from any suface?

From a textbook I read something like this: "When sunlight is reflected from a horizontal surface, the plane of incidence is vertical, and the reflected light contains a preponderance of light that is ...
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27 views

How to design a grating coupler to produce surface plasmon-polaritons (SPPs) at a desired frequency?

Following on from this question, which I found very useful on the topic, I was wondering how you would use the equation $\beta = k sin \theta \pm \nu g$ to fabricate a grating coupler to generate SPPs ...
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36 views

How to understand that the electromagnetic wave propagates?

Don't the electric field and magnetic field have infinite range? When a charged particle moves, the electric field vectors at two different locations A and B should start to change at exactly the same ...
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1answer
51 views

Current Electricity

If $$ \frac{dQ}{dt} = I $$ and if an accelerated current produces E.M. waves (radiation), does that mean $d^2Q/dt^2$ (second derivative of a charge w.r.t. time) will give me the magnitude of the wave ...
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1answer
18 views

Correct terminology for when neutral atom is ionized due to an electric field?

An electric field will cause an induced dipole in neutral atoms when present - I presume that if the field were strong enough the magnitude of the polarization could exceed a critical length and cause ...
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15 views

Show that the electric dipole term vanishes for a particular current

I'm interested to show that given a ring with radius a where there's a current $I_0 \cos \omega t$ ($I_0$ is a constant) there is no radiation due to the electric dipole term (appearing in the ...
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24 views

Counting modes Rayleigh-Jeans

In the derivation of the Rayleigh-Jeans Law, we count the number of EM modes in a square cavity. After calculating the number of allowed modes due to boundary conditions, we multiply it by a factor of ...
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3answers
69 views

Question about intensity of EM waves

For electromagnetic wave if it's reflected from a perfect conductor standing wave can be form. I wonder why Poynting vector can be used to describe the intensity of standing EM wave. (see p.19 of ...
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1answer
51 views

What is the mix of ordinary mass vs. ordinary radiating energy in the universe?

I have seen data showing that the estimated mix of dark energy in the universe is 68.3%, the mix of dark matter is 26.8% and the mix of ordinary matter is 4.9%1. However, within "ordinary matter," ...
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27 views

mixing colour of light

I have seen blue and yellow colours mix to form a light green shade. How can we explain this phenomenon, both in case of light and physical substances like paint ?
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will osmium or lead stop all high-energy photons in a shorter distance?

I remember seeing a similar question to this one on Physics StackExchange once. Most of the answers were to the effect of "I don't like the way this question is phrased, so I will insult your ...
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1answer
33 views

Can light (electromagnetic radiation) cause electromagnetic induction in a wire?

Can light, as an electromagnetic wave, cause electromagnetic induction in a wire by passing near the wire? Does a moving electromagnetic wave cause a varying magnetic field in the region near the ...
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2answers
71 views

Do all the electromagnetic radiations have dual nature i.e. particle nature & wave nature?

I have studied the dual nature of the light as particle nature & wave nature. A photon of light energy can knock a single electron out of certain metals (usually having less ...
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28 views

Wideband metamaterials in mobile-telecommunications bands

Were there any metamaterials (materials, settings, geometry) studied that are non-resonant (not frequency selective) in the frequencies between 700 MHz and 2700 MHz, therefore useful for mobile ...
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1answer
30 views

Layer of graphene on reflector of an antenna

First of all I have no idea how well graphene "sticks" to other metals, but let's suppose it does (well, if I may please ask you to reply to the "stick" question too...). Given the material great ...
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1answer
44 views

What color does graphene glow when heated?

If you heat graphene hot enough, what color would it glow? Is the color within the visible range?
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What is difference between Irradiation & Radiosity?

I have a question in Radiometry: What is difference between "Irradiation" & "Radiosity" in Radiometry? Assumption: the emission & the reflection are specular. I know these physical ...
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23 views

Why are most antennas in cellular networks +/- 45° polarized?

I've just been asked a strange question that I cannot find an answer to (even on the internet it seems I can't find any explanation for this) and I ended up wondering why most of the antennas which ...
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1answer
49 views

What is the strength of the magnetic field required to penetrate an average human body?

Introduction Suppose you are an experimental nanobot researcher trial-ling a new form of medication that involves activation and control of nanobots within the cells of the interior of the human body ...
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1answer
104 views

What does a light wave look like (3d model)

What does a light wave look like? The only models I can seem to find online are 2D waves, they just look like sin() graphs. I have seen the models of the two components of "light waves" (electric ...