All Questions
Tagged with electromagnetic-radiation optics
712
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How to measure light intensity in a room?
Does anyone know how I would go about measuring the light intensity in a room? I'm not interested in knowing the lux reading, I would like to measure the $W/m^2$ due to thermal radiation in my ...
- 31
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4
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133
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Reflection due to wave nature of light
In my high school, I am studying geometrical optics. I studied why smooth surfaces like mirrors form an image of an object but rough surfaces like a wall don't (due to regular reflection and irregular ...
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Light waves can't have a wavelength
The wave nature of light comes from Maxwell's equations. More precisely, the two wave equations that come from them:
$$\Delta\vec{E}=\mu\varepsilon \frac{\partial^2\vec{E}}{\partial t^2}\\
\Delta\vec{...
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Why are Fresnel coefficients not symmetric?
When talking about reflection, we have the following coefficients for the electric field:
$$r_{\perp}=\frac{n_1\cos(i)-n_2\cos(t)}{n_1\cos(i)+n_2\cos(t)} \\ r_{\parallel}=\frac{n_2\cos(i)-n_1\cos(t)}{...
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How can a greater than 1 reflectance coefficient be explained in $\rm SiC$-$\rm SiO_2$ interface?
I ran a simulation using the Transfer Matrix Method to plot the R,T and A curves for a SiC->SiO2 interface. There's a region of incident energies where the |r|^2 I get is higher than 1 and the ...
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1
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Absorption and emission spectrum
I was wondering how do you see a spectrum when light is passed through a substance. Like most of the substances we use are opaque, so how does light pass through them without being reflected? Also ...
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Ray separation in waveplates
In a birefringent medium, the ordinary and extraordinary rays have different Pointing-vector directions and, therefore, different propagation directions, since the direction of the Poyting-vector ...
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Why isn't the original EM wave in a beam of light in a medium not still detectable from a distance as if it were moving at the speed of light?
I'm learning optics and I've been told that the reason light slows down in glass is because the Electromagnetic field of a beam of light interacts with and accelerates charged electrons in glass ...
- 531
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Intensity of non-monochromatic electromagnetic radiation
The intensity of a monochromatic electromagnetic wave is given by
$$ I \equiv \langle S \rangle = \int_{t_0}^{t_0+T}c\epsilon_0 E_0^2 \cos^2(kx-\omega t) \text{d}t = \dfrac{c\epsilon_0}{2}E_0^2. $$
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Effect of incident angle on wavelength of transmitted wave for normal polarisation?
In my electrodynamcis assignment I'm being asked to derive the wavelength of a normally polarised wave transmitted through a glass/air interface as a function of $n_1$ (the refractive index of the ...
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Is sky still blue when the line-of-sight is perpendicular to the sunlight ray?
We model molecules in the atmosphere, excited by sunlight, as tiny dipoles, which radiate as ~ $\omega^4 \sin^2 \theta$, where $\omega$ is the angular frequency and $\theta$ is the angle between line-...
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QFT view of lower light speed of light in medium [duplicate]
In classical EM theory, if we have a medium whose dielectric coefficient is independent of wavelengths (suppose we filter the incoming signal to a certain frequency band), then the waveform gets to ...
1
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1
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45
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Why do we see objects with a given color?
I'm currently studying Electromagnetic Optics, and I don't quite understand the (classical) process through which we perceive an object with a given color. From my understanding, I'd make a ...
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Polarization of electric field and its effect on the Poynting vector
To preface, I've little experience with optics. This is a very use-case specific project I'm undertaking. So, if there are any improvements in my method, I'd appreciate it!
I'm working with the vector ...
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How does an electromagnetic wave behave when it enters a medium with refractive index less than unity?
From what I am able to find, the phase velosity of the wave exceeds c, but the group velosity remains less than c. However, why does the wave form wavepackets after entering a medium with refractive ...
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