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  2. Rotations and reflections in two dimensions - Wikipedia

    en.wikipedia.org/wiki/Rotations_and_reflections...

    An xy-Cartesian coordinate system rotated through an angle to an x′y′-Cartesian coordinate system In mathematics, a rotation of axes in two dimensions is a mapping from an xy-Cartesian coordinate system to an x′y′-Cartesian coordinate system in which the origin is kept fixed and the x′ and y′ axes are obtained by rotating the x and ...

  3. Cell wall - Wikipedia

    en.wikipedia.org/wiki/Cell_wall

    A plant cell wall was first observed and named (simply as a "wall") by Robert Hooke in 1665. [3] However, "the dead excrusion product of the living protoplast" was forgotten, for almost three centuries, being the subject of scientific interest mainly as a resource for industrial processing or in relation to animal or human health.

  4. Ewald's sphere - Wikipedia

    en.wikipedia.org/wiki/Ewald's_sphere

    the diffraction angle for a given reflection, the reciprocal lattice of the crystal. It was conceived by Paul Peter Ewald, a German physicist and crystallographer. [1] Ewald himself spoke of the sphere of reflection. [2] It is often simplified to the two-dimensional "Ewald's circle" model or may be referred to as the Ewald sphere.

  5. Lambertian reflectance - Wikipedia

    en.wikipedia.org/wiki/Lambertian_reflectance

    Diagram of Lambertian diffuse reflection. The black arrow shows incident radiance, and the red arrows show the reflected radiant intensity in each direction. When viewed from various angles, the reflected radiant intensity and the apparent area of the surface both vary with the cosine of the viewing angle, so the reflected radiance (intensity per unit area) is the same from all viewing angles.

  6. Angle of incidence (optics) - Wikipedia

    en.wikipedia.org/wiki/Angle_of_incidence_(optics)

    Focusing X-rays with glancing reflection. When dealing with a beam that is nearly parallel to a surface, it is sometimes more useful to refer to the angle between the beam and the surface tangent, rather than that between the beam and the surface normal. The 90-degree complement to the angle of incidence is called the grazing angle or glancing ...

  7. Total internal reflection - Wikipedia

    en.wikipedia.org/wiki/Total_internal_reflection

    Fig. 1: Underwater plants in a fish tank, and their inverted images (top) formed by total internal reflection in the water–air surface. In physics, total internal reflection (TIR) is the phenomenon in which waves arriving at the interface (boundary) from one medium to another (e.g., from water to air) are not refracted into the second ("external") medium, but completely reflected back into ...

  8. Reflection (physics) - Wikipedia

    en.wikipedia.org/wiki/Reflection_(physics)

    Reflection of light is either specular (mirror-like) or diffuse (retaining the energy, but losing the image) depending on the nature of the interface.In specular reflection the phase of the reflected waves depends on the choice of the origin of coordinates, but the relative phase between s and p (TE and TM) polarizations is fixed by the properties of the media and of the interface between them.

  9. Specular reflection - Wikipedia

    en.wikipedia.org/wiki/Specular_reflection

    Specular reflection, or regular reflection, is the mirror-like reflection of waves, such as light, from a surface. [ 1 ] The law of reflection states that a reflected ray of light emerges from the reflecting surface at the same angle to the surface normal as the incident ray, but on the opposing side of the surface normal in the plane formed by ...