Physical Science 20 Unit 1 Light and Waves.notebook
5. Reflection in a Plane Mirror
Obj: I can draw a ray diagram Recall:
Laws of Reflection
The angle of incidence is equal to the angle of reflection.
­ the angles are formed between the rays and the normal
­ the normal is an imaginary line perpendicular (90o) to the mirror 1
Physical Science 20 Unit 1 Light and Waves.notebook
important terms to know:
incident rays ­­­> light goes into the mirror reflected rays ­­­> light that bounces off the mirror, reflected plane mirror ­­­> "flat" mirror
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Physical Science 20 Unit 1 Light and Waves.notebook
Why isn't everything a mirror?
incident rays reflect parallel to one another
incident rays do not reflect parallel
specular reflection or diffuse reflection
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Physical Science 20 Unit 1 Light and Waves.notebook
object paper
specular or diffuse reflection
object specular or diffuse reflection
mirror
sunset 1
face
sunset 2
pool of water
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Physical Science 20 Unit 1 Light and Waves.notebook
Characteristics of Images for Plane Mirrors:
P.O.S.T.
1. Position:
­ the distance from object­to­mirror is the SAME as from the mirror­to­
image 2. Orientation:
­ the image is upright (right side up) and laterally inverted (mirror image)
3. Size:
­ as long as the mirror is at 90o , the object and image have the same height or size
4. Type:
­ the image is virtual (the light doesn't really come from behind the mirror, although it looks like it does)
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Physical Science 20 Unit 1 Light and Waves.notebook
Laterally inverted image
why?
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Physical Science 20 Unit 1 Light and Waves.notebook
Ex 1: Using a protractor and a straight edge draw the reflected ray
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Physical Science 20 Unit 1 Light and Waves.notebook
Drawing Ray Diagrams for Plane Mirrors:
1. Locate the image
­ draw the image...
­ the same distance away as object
­ the same height as the object
­ laterally inverted
2. Draw rays (straight lines) from the eye to the top of the image
­ solid lines in front, dashed lines behind the mirror line
3. Draw a line from the mirror back to the top of object
­ solid lines in front 4. Repeat steps 2 and 3 for the 'bottom' of the object
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Physical Science 20 Unit 1 Light and Waves.notebook
Ex 1: Draw a ray diagram for the following: 0
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0°
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Physical Science 20 Unit 1 Light and Waves.notebook
Ex 2: Draw a ray diagram for the following: 0
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0°
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Physical Science 20 Unit 1 Light and Waves.notebook
Images From 2 Mirrors at Right Angles
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Physical Science 20 Unit 1 Light and Waves.notebook
Ex 3: Draw a ray diagram for the following: 12