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

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### Are Transmission values for absorptive light filters proportional to Intensity?

Mostly filter rates are given in percent, but if I imagine that for example 10 photons hit an absorption filter with 50%, molecules are excited there and in the end only 5 get through while the other ...
1 vote
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### How can we prove for magnification of an astronomical telescope?

It is known that when we increase the length of the tube of an astronomical telescope the magnifying power decreases, how do we prove it?
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### Gravitational convergence of light

light has a non-zero energy-stress tensor, so a flux of radiation will slightly affect curvature of spacetime Question: assume a flux of radiation in the $z$ direction, in flat Minkowski space it ...
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### What is the smallest possible wavelength? [duplicate]

I was thinking about this the other day after a quantum mechanics lecture (unrelated to the lecture I was taking) and pondered "Is there a minimum wavelength for a photon?", through ...
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### Can the temperature of a body become lower than the temperature of the surrounding air?

In winters, frost is formed on the grass and wood and not on concrete roads.Temperature of frost is lower than the temperature of the surrounding air.So a question arises ""Can a body become ...
57 views

### How does Planck's Constant solve the ultraviolet catastrophe?

I am studying black body radiation and a high school level for a class. My understanding of it is this: There is a finite frequency light and therefore amount of ultraviolet light objects can emit. ...
1 vote
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### Reflection at a conducting surface

The boundary conditions that we used to analyse reflection and refraction at the interface between two surfaces are: $\epsilon_1 E_1^\perp + \epsilon_2 E_2^\perp = \sigma_f$ where $\sigma_f$ is the ...
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### Laser induced explosion (detonation)

I have a question involving quite the wacky (and silly) hypothetical. It's a part of an ongoing argument I'd like to settle. Of course, I have no background in physics which is why I came here, so I ...
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### Question regarding synthetic UV sources (fluorescent, LED) and claims to "match the sun"

I am involved with some discussion regarding lamps specifically in use for reptiles. Captive reptiles can often suffer from hyperparathyroidism from a lack of vitamin D. The safest way found to ...
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### How do i calculate change of momentum when I send a photon in the direction of travel

Say a spaceship is traveling at a certain velocity v (>>c) and it emits light from the nose of my spaceship in the direction of travel. The speed of light is finite and hence there should be a ...
179 views

### What is the potential energy of electromagnetic waves traveling in air?

The Lagrangian for electromagnetic waves shows that its energy has a kinetic part as well as a potential part (just like everything else). The potential part only exists in a medium whereas in the ...
1 vote
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### How exactly are incident EM waves cancelled by a conductor, and why only on one side of it?

This answer describes why EM waves from inside a microwave are blocked by the metal mesh screen: The incident EM wave induces oscillations in the metal of the screen, and these oscillations reradiate ...
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### Tangential component of the "electric" vector spherical harmonic $N_{lm} = \nabla \times (h X_{lm})$?

So I want to solve the problem of an electromagnetic plane wave scattering by a sphere myself, and one of the crucial steps is to solve the scattering of a converging TE- or TM-polarized vector ...
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### Interpretation of watts per square meter for intensity of radiation

The energy that an electromagnetic field can deliver to a system is proportional to the square of the field. However, we use the terminology watts per meter square to represent the amount of energy ...
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### Photon emission rate frequency dependency

I am puzzling over the dependence of the energy flux of electromagnetic radiation on the frequency of the source. The power radiated in any direction or solid angle from a charged particle ...
How EM waves are produced say by a capacitor of an LC circuit here if $E$ is increasing in upward direction? My thoughts Thought 1:- If E is increasing E flux is increasing thus B field must be ...