Review

Can you name this wave phenomena?

Interference or beats

B. Reflection

 [ Reflection ] Show Me The Physics Webite

1. Law of Reflection

a.  θ of incidence = θ of reflection

 [ HTML5 ] showmethephysics.com

Use the acute angles on your protractor /p>

Charles William Weick Elementary Mechanical Drawing, Theory and Practice
(New York: McGraw-Hill Book Company, 1915) 21

Line going through O, we will
refer to as the baseline

 θin = θincidence (angle incoming normal ray  makes with the normal) θref = θreflect (angle reflected light makes with the normal)

Ray Diagram  - Reflection

Remember ...

... reflection always makes a V

What is the smallest mirror
you need to see your whole body?

Click and Drag Gecko

The image from a plane mirror:

a. Virtual (realistic) & Upright (Straight up and down)

b. Incident ray, normal line, and reflected rays are all in the same plane

Source: Elroy M. Avery School Physics (New York: Sheldon and Company, 1895) 77

Clipart ETC

c. The distance the object is in front of the mirror equals the distance the image is behind the mirror

2. Two Basic Kinds of Reflection

a. Regular Reflection – reflection off a polished surface (produces images)

Regular Reflection Produces Images

http://www.freeimages.co.uk/

b. Diffuse Reflection – reflection off an irregular surface causing light to scatter (no image)

 Which letter correctly shows reflection?

Ray C

 Angle of Reflection?

60 degrees
(Angle from normal)

Dr. Carlson - Purdue University