Chapter 28 Refraction and Reflection Reflection i r

Chapter 28 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 • 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

Beach Water Whoa Baby Help

Refraction i R air ni water n. R

Index of Refraction n= speed of light in vacuum speed of light through medium n=c/v³ 1 Snell’s Law ni sin qi = n. R sin q. R

Because of atmospheric refraction, we have lingering, elliptical sunsets. Sun Earth

Sunset

Mirage Cool air Warm air Surface of water?

Looming Warm air Cool air

960

Total Internal Reflection Critical Angle

Two Prisms in a Monocular

Dispersion in a Prism

Mercury Near Horizon

Rainbows

Green Flash Sun Earth 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.

Green Flash

Lenses Converging Lens

Lenses Diverging Lens

Ray Diagramming f Principal axis Applet 1

Double Convex Double Concave Plano Convex Plano Concave Convex Meniscus Convex lenses are positive converging lenses. Concave lenses are negative diverging lenses. Concave Meniscus

Lens Defects white Chromatic Aberration Spherical Aberration