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Actually, this is a nice question $-$ why do the dimensions of the slit or a hole (which are transverse to the direction of your incident plane waves) limit possible range of wavelengths (which are longitudinal, between two EM planes) of the transmitted wave. Without deriving the behavior from wave equations which would do the job, one may say that it's due ...

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Another, better way, (because imo, the wiki line you quote is a bit obscure) of dealing with your question is based on John Baez's Notes: The Compton wavelength of a particle, roughly speaking, is the length scale at which relativistic quantum field theory becomes crucial for its accurate description. A simple way to think of it is this. Trying ...

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The simple physical model of the eye (or indeed a typical camera) is that it records just three values for each pixel. In your eye, this is because you have three different types of cone cells, called S, M, and L, peaking in blue, green, and red wavelengths. In a camera, the light is passed through blue, green, and red filters before having its intensity ...

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In Minkowski spacetime, the spacetime interval of lightlike movements is zero. That means, from the (hypothetical) point of view of a massless particle such as a photon, it does not even exist one Planck time. At a proper time zero, any wavelength becomes meaningless, even if the physical process is the same that we observe. For the answer you have to take ...

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We don't really have a good perspective on what a photon "feels" or, indeed, anything about what its universe would look like. We're massive objects; even the idea of "we must travel at the speed of light because we're massless" makes little sense to us. But we can talk, if you like, about what the world looks like as you travel faster and faster: it's just ...

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Unfortunately, I think you are speaking about what people commonly say is "Huygen's Principle", "In order to explain waves diffraction, it says that every point in a wave front behaves as a source, so the next wave front is the sum of all secondary waves produced by these points.", but this is not actually what Huygen's principle says. Huygen's principle ...

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First off I think I should sort out a misconception about Huygens Principle. You can apply this principle efficiently if you have a slit, which is equal or smaller than the wavelength you are considering. If on the other hand the slit is substantially larger than the wave length, you should consider multiple Huygens sources. Take a look at this animation ...

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You're not missing anything. You are right, $k=\omega/c$. The argument $\sqrt{\frac{\omega ^2}{c^2}-k_z^2}$ in the Bessel function is the projection of the wavevector onto the radial direction. The use of Bessel functions beclouds what's going on a bit. Recall that a plane wave with wavevector $\vec{k}$ has the functional variation $\psi(\vec{r}) = ... 0 So the length of a wave is the distance between two compressed regions as shown in this representation of a longitudinal wave: is in general not true but rather it is a pictorial representation for simple cases in one dimension. A wave is any solution of a wave equation of the form$\Box \psi(\textbf{x},t) = 0$that can be expressed in the form$$... 4 You don't need a particular point on the wave. You only have to make sure it's the same point on each successive wave. If you have a microphone, hooked to an oscilloscope, you can measure the time between peaks (or troughs, or zero-crossings), multiply by the speed of sound, and that's your wavelength. 0 There are a couple of ways of knowing the wavelength of laser pointer. 1) Using Snell'law (law of refraction): A light passing the border between two media whose refractive indexes vary. The incident light PO of wavelegth,$\lambda_{1}$travelling in a media of refractive index,$n_{1}$is refracted in to another media of refractive index,$n_{2}\$, with a ...

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