1. PW2 - Reflection

2.  The angle of incidence is equal to the angle of reflection.  The incident ray, reflected ray, and normal all line in the same plane.

3.  incident ray - a ray approaching the surface  point of incidence - the point where the incident ray strikes the surface.  normal - a perpendicular constructed where the incident ray strikes the surface.  reflected ray - a ray that leaves the surface at the point of incidence.  angle of incidence - the angle between the incident ray and the normal.  angle of reflection - the angle between the reflected ray and the normal.

4.  Regular (specular) reflection:  is when all the rays in a beam of light are reflected at the same angle  occurs in smooth surfaces (i.e.: mirrors).  Diffuse reflection:  occurs when the rays in a beam of light are scattered off a surface.  occurs in rough surfaces (which is much more common)

5.  This is why you see increased glare when driving in the rain or icy conditions.  For the purposes of this unit, we will focus on REGULAR REFLECTION

6.  Plane Mirror:  a flat smooth surface that reflects light in a regular or specular way.  Most common, found in bathrooms, dressing rooms, automobiles, etc.

7.  Virtual Images:  The images formed in a plane mirror appear to be behind the mirror. This means that the light appears to be coming from behind the mirror.  We call images formed in this fashion virtual images. A virtual image is an image that light does not pass through, but only appears to pass through.

8.  The four (4)characteristics of images in a plane mirror are:  1) same size as object  The dimensions of the image are equal to the dimensions of the object. Magnification is 1.0.  If a 1.6 metre tall person stands in front of a mirror they will see an image that is 1.6 m tall.  2) erect (upright)  3) virtual (behind the mirror and cannot be projected on a screen)  The object distance, d o, is equal to the image distance, d i, and the image is directly across from the object (perpendicular to mirror). d o = d i  4) laterally inverted (right side of object is left side of image)

9.  Draw a perpendicular line from the object to the mirror.  Extend the perpendicular line behind the mirror.  Measure the perpendicular distance (do) from the object to the mirror.  Make the perpendicular distance to the image (di) equal to do.

10.  Draw a perpendicular line from the object to the mirror.  Extend the perpendicular line behind the mirror.  Find the image using do = di.

11.  Draw a straight line from the image to the top of the eye. (Be sure to use a dotted line one the image side of the mirror and a solid line on the object side of the mirror.)  Draw another line from the image to the bottom of the eye.  Where the “image to eye lines” strike the mirror, draw straight lines from the mirror back to the object.  Finally, draw arrows on the “object to eye ray lines” indicating the direction that light travels.

12.  Draw perpendicular lines from the top and bottom of the object to the mirror.  Extend the perpendicular lines behind the mirror.  Find the image using do = di. Use dotted lines to draw the image.

13.  Draw a straight line from the top of the image to the top of the eye. Be sure to use a dotted line on the image side of the mirror and a solid line on the object side of the mirror.  Draw another line from the bottom of the image to the bottom of the eye.

14.  Where the “image to eye lines” strike the mirror, draw straight lines from the mirror back to the object.  Finally, draw arrows on the “object to eye ray lines” indicating the direction that light travels.

15.  Use a ruler  Use a protractor  Use a pencil  For rays of light, always indicate the direction by using arrows  Label the mirror clearly, or add thatched lines  For rays behind the mirror, used a dotted line  Recall that the angle of incidence is the angle between the normal and the incident ray, not the mirror!  Likewise, the angle of reflection is the angle between the normal and the reflected ray, not the mirror!