Chapter+29+and+30

​**Key Definitions** **: **
 * 1) **__Reflection__** - a wave that reaches a boundary between two media, some or all of the wave bounces back into the medium.
 * 2) **__Refraction__** - the change of direction of a ray of light, sound, heat, or the like, in passing obliquely from one medium into another in which its wave velocity is different.
 * 3) **__Virtual image__** - an image from which rays of reflected or refracted light appear to diverge, as from an image seen in a plane mirror.
 * 4) **__Real image__** - an optical image formed of real foci
 * 5) **__Total internal reflection__** - the effect that occurs when light meets the interface between the medium in which it is traveling and a medium of smaller refractive index at an angle of incidence greater than the critical angle, all light being reflected back to the first medium

**Notes:**
 * Most materials offer total reflection off a rigid surface with some absorption (opaque)
 * Specular Reflection is what occurs off a mirror or window
 * Diffuse Reflection is what occurs off a road, paper and water
 * Objects can be seen by the light they emit, or, more often, by the light they reflect.
 * Most objects exhibit diffuse reflection, with light being reflected in all directions.
 * The image in a plane mirror is always the same height, same distance away as the object in front of it,and the same color
 * The image is also right side up and virtual
 * Focal points are always positive except for convex mirror
 * Real image is positive and virtual image is always negative for distance
 * when a ray of light goes into a less dense medium then it bends away from the normal
 * the incident ray, the refracted ray and the normal all lie in the same plane

**Pictures:**

 //Converging and diverging lenses. Parallel rays enter a convex lens converge and meet at the principle focus. The distance between the center of the lens and the principal focus is the focal length. Parallel rays entering a concave lens diverge and never meet.//




 * Links: **

[] talks about the shape of a transparent object

[] (law of reflection)

[] how mirrors work

[] curvature of wavefronts


 * Test Questions: **

a. Convex b. Concave c. Plane
 * 1) a mirage is caused by reflection? true/false
 * 2) reflection off the road is diffuse reflection? true/false
 * 3) a real image is up right? ture/false
 * 4) The mirror on the passenger side of a vehicle is

5. Fiber optic cables use _ to transport information faster and more efficiently a. Total internal reflection b. Refraction c. Reflection d. All of the above

6. At night when the air is cooler over the surface of the lake, sound is (refracted/reflected)?

7. A swimming poool apperas (shallow/deeper) than it actually is?

 d. A and C
9. If an image is upside down, the image is.

10. If an image is right side up, the image is.

**Record the aswers to the above questions at the link below** Answers to Test Questions