2. Circular wave fronts

3. Plane wave Fronts Produced in a Ripple Tank

4. Wave Fronts and Rays 1.Wave fronts are lines (or surfaces) marking the location of the crests in a wave. 2.Rays are lines that show the direction of travel. 3.Rays are always perpendicular to wave fronts spherical Plane Wave fronts Spherical Wave fronts

5. Law of Reflection - The reflected ray is in the plane established by the incident ray and the normal to the point of incidence. The angle of incidence, measured from the normal to the incident ray, equals the reflected angle, measured from the normal to the reflected ray.

6. Law of Reflection

7. Law of Reflection:  i =  r

8. Types: 1.Specular (regular)Reflection – Reflection from a smooth, polished surface like a mirror. The incident rays come in parallel and reflect parallel. 2.Diffuse Reflection – Reflection from a rough, unpolished surface like paper. The incident rays come in parallel but reflect in different directions.

9. smooth surface rough surface Diffuse reflection: rough surface has many different “angles” so reflected light can be seen at a variety of locations Specular reflection: smooth surface has only one good angle for reflected light to enter your eye

10. Link

11. 1.If the angle between the incident ray and the reflected ray is 80 0 in the diagram, what is the measure of the reflected angle? 2.Find: a.The reflected angle from mirror 1. b.The reflected angle from mirror 2.

12. 3.The diagram below shows a ray of light being reflected from a plane mirror. Which letter indicates the angle of reflection? a.A b.B c.C d.D 4.The diagram below shows a light ray being reflected from aplane mirror, what is the angle of reflection? a.90  b.80  c.50  d.40 

13. 5.Which diagram best represents Image I, which is formed by placing object O in front of a plane mirror? 6.A ray of light strikes a plane mirror at an incident angle of 35°. The angle between the incident ray and the reflected ray is ____. 7.Which of the diagrams representing light rays re­flecting from a surface illustrates diffuse reflection?

14. Reflections from mirrors

15. A husband and wife are shopping for a mirror so that they can view their entire height at one time? The husband is 75.5 inches tall and the wife is 66.7 inches tall. What is the minimum length of mirror that would satisfy both of them? Assume they are both standing upright and their eyes are located 4 inches below the top of their heads?

16. 1.The image is as far behind the mirror as the object is in front of the mirror 2.The image is upright, 3.There is left right reversal 4.The image is the same size as the object. 5.The image is a virtual image

18. Plane Mirror Ray Diagram  Draw 2 sets of rays from object  Perpendicular to mirror and back to the eye using the law of reflection  Extend rays back to where they meet  Results: p = q h = h' M = 1 h p h'h' q  

19. Plane Mirror Ray Diagram 1. Image is upright, virtual, unmagnified 2. Image is behind mirror a distance equal to the object-mirror distance (p = q ) 3. No left-right reversal, but there is a forward-backward reversal h p h’ q  