Light

• light is an electromagnetic wave that spreads without medium

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Properties of the light:spread according to straight line, has energy, can be seen, spread in the form of radiation, has spreading direction perpendicular to vibration direction, can experience reflection, refraction, interference, difraction, polarization.

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bodies that can spread light is called liht source. while bodies that cannot spread light their selfis called dark body.

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the kind of dark bodyif hit by the light:opaque body, transparent body, clear body.the law of light reflection:1. incident ray,normal line, and reflected ray lie on one flat plane. 2. incident angle is equal to reflected angle.

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light reflection is separated into two kinds, those are specular reflection and diffuse reflection.

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properties of image in the flat mirror:virtual, upright, the same size, facing perverted to the object, object distance to the mirror is equal to image distance to the mirror.

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concave mirror is called also convergent mirror, because the concave mirror has property of collecting light or the rays it reflects.

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three particular rays in the concave mirror namely:(a) incident ray parallel to main axis of mirror will be reflected through focal point F.( b) incident ray through focal pont F will be reflected parallel to main axis.(c) incident ray through center point of mirror curvature P will be reflected back through the center point of curvature.

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convex mirror is called also divergent mirror, because convec mirror has property spreading the light strikes it

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three particular rays in the convex mirror namely:(a)Incident ray parallel to main axis is reflected seemed from the focal point (F). (b)incident ray goes to focal point (F) is reflected parallel to main axis.(c)Incident ray goes to center point of mirror curvature P is reflected back seemed comes from the center point of curvature.

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the image formed by a convex mirror is always has property of virtual, upright, and minimized.

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In the concave mirror and the convex mirror hold the formula : 1/f = 1/So + 1/Si or 2/R = 1/So + 1/Si

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Image magnification in the concave mirror and the convex mirror is formulated as follows: M = Si/So = hi/ho.

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light refraction is the light bending that spreads from one medium to another medium of different density.

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Snellius Law : (a)Incident ray, refracted ray, and normal line lie on one flat plane and those three intersect at one point.(b)Ratio of projection of incident ray and refracted ray at boundary plane between two mediums is constant number (index of refraction).

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Lens consist of two kinds, those are convex mirror and concave mirror.

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The ability of a lens in collecting or spreading it receives is called the power of lens. The power of lens is formulated as folllows. P = 1/f