Reflection Get Ahead Lecture California Content Standards: 4f Students know how to identify the phenomena of refraction and reflection and know that these are characteristic wave properties. Discuss how slides becoming more of outlines of what is said and that will need to listen more carefully because of this. We are moving to being able to take good notes even when speaker doesn’t give you any.

Reflection in General Definition: bouncing of wave off an interface. Velocity, frequency and wavelength remain constant. Law of reflection Define reflection. How do the frequency, wavelength and velocity of the incident wave compare to the reflected wave? State the law of reflection. Distinguish between a specular and diffuse reflection and give examples of each. Show transparency and define reflection as bouncing of wave. Discuss how velocity, frequency and wavelength all will remain the same for the incident and reflected wave since they are in the same medium. Write equation for law of reflection and define the incident and reflected angle from the normal to the interface Draw two pictures showing parallel waves bouncing off a rough and smooth surface. Define specular and diffuse reflection using these pictures. Give examples of each including waxed vs unwaxed floor, shiny vs rough paper and wet vs dry road. Discuss breifly how the relative size of the wave (wavelength) determines the smoothness of a surface. 1/8 th wavelength = smooth All waves can be refracted

Specular and Diffuse Reflections All rays reflected parallel to one another off smooth surface Examples include plane mirror, gleam off polished floor and glare off wet asphalt road Rays reflected at different angles relative to one another off rough surface Examples include unwaxed floor, dry asphalt and newsprint Question: Distinguish between specular and diffuse reflections. Give examples of each.

Reflection of Sound Echo Amphitheatre Sound Balls and Half Shells Krikorian Theatre sound baffles eliminate reflections Upward sloping ceiling directs reflections to back where absorbed Questions: Describe some ways that reflection is used to control sound.

Plane Mirrors Plane Mirror Virtual Image Image and Object distance same Image and Object sizes same Reverse front-back Question: Describe the image of a plane mirror. Specifically is it real or virtual, magnified or reduced, erect or inverted. How do the image and object distances for this type of mirror compare? Does this type of mirror flip front and back or left and right?

Curved Mirrors Converging Mirror Diverging Mirror Thinnest in middle Reduced or magnified image Real or virtual image Inverted or erect image The FAT mirror Mirror Diverging Mirror Thickest in middle Reduced image Virtual Image Erect image The THIN mirror Questions: Draw the shape of a diverging or convex mirror. Describe the image from such a mirror. Draw the shape of a converging or concave mirror. Describe the three types of image this mirror can produce.