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title: 'laws of reflexion and refraction, and associated phenomena'
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#### course to build

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There, to see. The laws of the reflection and the refraction were correctly expressed at the previous level, with beautiful gif in the part(party) F. Thus in priori, possibly a link towards this specific page of the lower level (hill). And as a result, in N-1 we shall call the level even lower (plain).

On the other hand, it is maybe the moment to reveal more on the inadequacies of the geometrical optics. One level hill, we said that the light is passed on(transmitted) through a diopter according to the law of Snell-Descartes, and reflected about a mirror. In fact, even on a diopter, a part(party) of the energy is reflected and the other one is refracted. Even by limiting itself to the visible, we see that this distribution of the energy depends of angles of incidence (make look at the window of a window, we see through and we see inside, make vary the angle of vision with regard to(compared with) the normal for the window). It is important because it brings the images parasites ( ghosts ), and coats(layers) anti-reflection of corrective lenses or lenses of objectives for example. It is for this level q' it is necessary to speak about it.

Then, it is already necessary to introduce the ray-tracing. Which(who) will be better developed at the level mountain. But it is important to speak about it here. Even to quote him(it) in two words at the level hill, because the youngest have access to the tracing ray easily.

And it is best (?) that one can make in geometrical optics. Because later, we are going to go farther with him(her,it) " oprique geometrical paraxiale ", but it is the "idealized image" which allows to visialiser, to plan, to size much more. But as it is an idealized image, then there is écarts with the reality, which are called the aberrations. (Not, it is a little more, the aberrations). To speak about aberration in the geometrical optics with the only laws of the reflection and about the refraction, really has no sense(direction). To reflect as build it :)

**It is also possible to propose a change in the structure of chapters and sub-chapters**
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