RECALL
OUTLINE Ray model & depth perception Reflection
law of reflection mirror images
Polarization
REMINDER Set your clocks ahead one hour Sat
night
Ray Model of Light Light travels in a straight line.
… while in single material Ray is an arrow in direction of motion narrow laser beam travels straight
Light travels in a straight line.light from bulb -- each bit travels straight
Ray Model of Light
evidence = shadows. No light behind object
Depth Perception
Rays from nearby object strike two eyes at very different angles Rays from distant object strike two eyes at nearly same angle
Perceive rays as traveling straight to eye
Ray Model
Ray changes direction when it hits a new material Often some
reflected and some refracted look at transparent
surface like water
Geometry for single ray The normal line is a line
perpendicular to the surface between the two materials
Angles Angle of incidence (1): the
angle between the incident ray and the normal
Angle of reflection (1’): the angle of the reflected ray and the normal
Angle of refraction (2): the angle of the refracted ray and the normal
Reflection Reflected Ray obeys law of reflection
angle of reflection = angle of incidence angles measured relative to normal
normal is perpendicular to surface
Compare to ball bouncing.If it comes in perpendicular, it leaves perpendicular (=0)Otherwise bounces at same angle on other side of normal.
Images in Plane Mirror Upright Same distance behind mirror as object is
in front Generally “front” is side light comes from.
Same size as object Image is flipped over plane of mirror
Left and right are reversed. because front and back are reversed
Images in Plane Mirror
Based on depth perception.
Where do both the purple and the green rays appear to come from?
Images in 2-D corner Reflector
Can see an image in each mirror
Light can reflect from each mirrors, then back to you.
creating images 1 & 2
And also see an image of image 2Both should be same place
Image 1
Image 2
Image 1
Image of image 2 in mirror 1
Then you also see an image of image 1
Images in Curved MirrorsA curved mirror that has its center farther away from you than its edges is called a concave mirror.A curved mirror that has its center closer to you than its edges is called a convex mirror
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