# Tag Info

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It's not the same photon but the same energy. After the electron absorbs the energy of a photon it later releases a new photon in a random direction.

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The general and easy rule to remember the sign convention for convex and concave mirrors and lenses or any optical component is thinking in terms of power. The power of an optical element is calculated by 1/focal length and the unit is dioptre (1/m). It is negative for components which diverge parallel incident rays of light and positive for components ...

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You can apply the Huygen's construction to any distance over which the local environment is optically homogeneous. Encountering a reflective or refractive surface is encountering a non-homogeneity, so you can't draw big circles that include a mirror or a lens. You can modify the Huygen's principle so that you can use near such boundaries, but the ...

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By denser, I assume you mean with a larger refractive index. The answer is established from the Fresnel equations giving the ratio of the electric field amplitudes. The reflection amplitudes for (for example) light travelling from glass to air can be either positive, negative or complex depending on the angle of incidence and the polarisation state of the ...

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This depends on the reflectivity of the objects and the size in the sky. The visual albedo of the moon when near (but not at) full, is about $0.12$. Earth's is around $0.39$. Being in low-earth orbit, the actual amount will vary based on the terrain and atmosphere. If it's overcast below, the value could be much higher. You can assume that a given area ...

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This Q boils down to How bright is Earthshine? According to the usual source Oceans reflect the least amount of light, roughly 10%. Land reflects anywhere from 10–25% of the Sun's light, and clouds reflect around 50%. So the amount of sunlight reflected (i.e. albedo) depends on what part of the earth is facing your observer and how cloudy it is. ...

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The energy is reflected due to the discontinuity of the string mechanical impedance. Therefore it "can't be used as a part of the pulse" because it never gets to the denser rope. It's actually a special case of very general principle: whenever there is a discontinuity in propagation medium, energy reflection occurs. That's the same in optics, when you are ...

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Try to think the rope made up of small solid balls connected with springs. When you make the bump as shown in your picture the springs are expanded. Now you let go of it. The rising ball applies force upward to the ball on its right. The already expanded springs soon tend to decompress again. In doing so the the falling ball applies a downward force to ball ...

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Seems like they've found a way to do it! http://phys.org/news/2015-11-device-theoretically-bit-infinite-amount.html The problem with my initial idea about using an ordinary container is described succinctly in the above article: When light is put inside a cavity, it basically interacts with the matter that surrounds it (e.g., glass or metal), and this ...

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It's simply because water is much flatter and smoother than most surfaces. You see reflections in water but not, say, sand, for the same reason you see your reflection in a polished piece of steel but not a rough-sanded piece of steel. All materials reflect light to some extent, but a rough surface scatters the reflected rays in all directions, so ...

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If the impedances are complex then it means you have dissipative terms. For example, if the problem was normal incidence from vacuum into a conductor, then energy conservation is not as simple as saying the (magnitude of the) Poynting vector of the incident wave equals the sum of the Poynting vectors in the transmitted and reflected waves. In a conductor, ...

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You only expect transmitted power to be equal to the incident power minus the reflected power when no energy is supplied to charges (which can then lose energy to heat). The Poynting vector does not have a divergence free energy flow, it can gain or lose energy by getting or supplying energy to charges. And the charges can give or get energy from the fields ...

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How a classical electromagnetic wave emerges from innumerable photons can be seen in this blog entry. It is not simple, one needs quantum field theory to start with. One should get the interaction of a single photon with a crystal lattice , and one can get a quantum mechanical solution, which will give the probability of the photon to scatter or go through ...

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First, it would have to be the case on the 3 side of the prism for the light get trap. Second, nothing is 100% transparent so the glass would finally absorb the light. Third, when an object is black the incoming light is trapped as well. And the object don't explode :-) When energy is absorbed, temperature rise. But when temperature rise, it escapes the ...

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