New answers tagged reflection
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Most of the signals one receives for TV broadcasts are going to be in the so-called Ku band (12 to 18 GHz).
Around 10 GHz is the absorption peak due to orientation relaxation of molecules in liquid water (More about molecules and microwaves can be found here).
Above 10 GHz, Lorenz-Mie scattering takes over. The effect is a noticeable degradation, commonly ...
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The electromagnetic waves that carry television, radio and WiFi signals are the same type of waves as the light waves that you eyes are sensitive to - they just have a longer wavelength. The water droplets in clouds, rain or fog disperse and absorb light waves, which is why you cannot see through clouds, and why you can see less far on a rainy or foggy day.
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I can't be sure without seeing the phenomenon, but believe that the colors that you are seeing do not originate in the glass window of your mobile phone. I think that they are caused by diffraction from the structures under the glass: the pixels of the display.
I will comment that dispersion of white light into colors does occur in a parallel slab. It is ...
2
The coffee table's surface is not very smooth. It has many microscopic bumps and crevices that reflect light in all directions, including back toward your eye. This is called diffuse reflection, as shown in the diagram below.
Light rays only all reflect in the same direction if the surface is smooth on a microscopic level. Mirrors are smooth enough for this ...
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It is surprising how long and convoluted the answers to this question are. It has to do with the fact that the question is not trivial. Some of the answers complicate matters by bringing depth to the discussion, which, in my opinion, should be kept separate or not brought into discussion at all.
A mirror does not flip a planar image either horizontally or ...
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(a) The principle is to consider two rays leaving a point at the bottom of the pool at small angles to each other, and therefore refract into the air at small angles to each other. One might emerge at 30° to the normal, the other at 31°. Suppose that these rays enter your eye. Draw these rays as dotted lines backwards through the water as if they didn't ...
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This equation:$\frac{Real\ depth}{Apparent \ depth}$=$\frac{\mu_1}{\mu_2}$
Is only valid for small angles.
Why?
Because in the derivation we approximate
sin($\theta)$~tan($\theta$)~$\frac{Real\ depth}{Apparent \ depth}$
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The basic idea is, you can think of the mirror as a window, when you look through it, you see the symmetric version of your own dimension. If the mirror is on the x-axis, the objects distance to the mirror will be the same on both sides;
if the object is at (4,9), its distance to the mirror is 9 units, meaning it will be 9 units away from the 'window' when ...
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A reflection grating is not a mirror. It is an array of reflective grooves in a surface. Light reflected from the bottoms of the grooves is delayed relative to light reflected from the tops of the grooves, just as light transmitted through optically thick portions of a transmission phase grating is delayed relative to light transmitted through the ...
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Yes, refraction does occur. Consider a silver mirror (medium 2) which has $$n = 0.051585-3.9046i$$ at 587.6 nm (red). For perpendicular incidence from vacuum (medium 1), $$k_{2z} = nk_{1z}$$ so there is a wave with an overwhelmingly imaginary wave vector. Therefore the refracted wave falls off exponentially to zero in less than one wavelength. Still, it is ...
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Yes, silver reflects because of the difference of its refractive index from that of air. However, silver is different from air or vacuum in that it is a lossy medium: it is conductive, so electromagnetic waves propagating in it induce currents, thereby losing energy and decaying in amplitude. This is conveniently modeled by a complex refractive index:
$$\...
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Simply putting the photons in a smaller box does not change the gravitational mass of the box + photons, because the box will contain the same amount of energy. This is not quite true, because when the photons are closer together they have lower gravitational potential energy, so the overall energy is very slightly reduced.
On the other hand, putting the ...
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It's not the reflections that make the box massive, it is the energy. If you put the same energy in a smaller box, the box isn't more massive.
Furthermore, it is not necessarily easy to describe what "a reflection" is in a small box, because radiation is a wave and does not undergo isolated reflection events, the way lots of fast bouncing balls in ...
2
This is the same as asking what would happen if the sun couldn't get rid of the heat it generates. In that case, the heat builds up, the sun's temperature goes up, and in response the sun expands a bit. This expansion causes the fusion reactions in the sun's core to slow down, which slows down the rate of heat generation. But if none of that heat can escape, ...
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What you have discovered is comatic aberration. It is similar to spherical aberration but occurs in both spherical and parabolic mirrors. If the incident rays are not parallel to the principal axis they are not focused to a point but rather to a comet shape which is the origin of the word coma, or comatic.
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