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Refraction and Reflection. Reflection. i. r. 1. Angle of incidence (i) = Angle of reflection (r) 2. Incident ray, normal, and reflected ray coplanar. Diffuse Reflection.
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Reflection i r 1. Angle of incidence (i) = Angle of reflection (r) 2. Incident ray, normal, and reflected ray coplanar
Diffuse Reflection • If successive elevations of a surface are no more than l/8 apart, then the surface is said to be polished at that wavelength. • Most objects are seen by diffuse reflection.
Ray Diagramming Plane Mirror
Plane Mirrors Object Image
Plane Mirrors • Image Properties: • Virtual • Erect • Same Size
Reflection from Curved Surfaces(Concave shown here) Ray Diagramming f Principal axis Reflecting Surface The law of specular reflection is still obeyed.
Fermat’s Principle • Light travels in straight lines and takes the path of least time. • Predicts both reflection and refraction
Help Help Help Beach Water
Refraction i air ni water nR R
speed of light in vacuum n = speed of light through medium Snell’s Law ni sin qi = nR sin qR Index of Refraction n = c / v ³ 1
Because of atmospheric refraction, we have lingering, elliptical sunsets. Sun Earth Sun
Mirage Cool air Warm air Surface of water?
Looming Warm air Cool air
Green Flash Earth Sun Dispersion occurs causing multiple images of the sun. The last to set would be blue, but most of the blue has been scattered which leaves green.
Total Internal Reflection Critical Angle
Lenses Converging Lens
Lenses Diverging Lens
Ray Diagramming f Principal axis Applet1
Various Lenses Double Convex Double Concave Plano Convex Plano Concave Convex Meniscus Concave Meniscus Convex lenses are positive converging lenses. Concave lenses are negative diverging lenses.
white Lens Defects Chromatic Aberration Spherical Aberration