Download light reflection plane mirror

LIGHT REFLECTION
Ray Model of Light
 light is represented as straight lines called rays
 ray diagrams are drawings that show the path that
light takes after it leaves its source
 light travels in straight lines until it strikes something
 some materials absorb light and other materials
reflect light
Regular Reflection
 light rays that strike a smooth surface
 they reflect light in the same direction staying parallel
to one another
 it is possible to see an image in the reflection (ex.
mirror)
Diffuse Reflection
 light rays that strike a rough/uneven surface
 they do not remain parallel, but are scattered in
different directions
 an image cannot be seen, but it still reflects light
Diagram:
 smooth, shiny surfaces (ex. mirrors, glass) allow you to
see an image
 image – a reproduction of an object produced by an
optical device (mirror)
 light rays bounce off a mirror
Law of Reflection:
When light reflects off a surface, the angle of incidence (θi) is
always equal to the angle of reflection (θr).
Mathematical Equation: (θi) = (θr)
Ray Diagram:
Reflection of a
single ray of light
in a ray diagram.
Normal – a dashed line drawn perpendicular to the mirror
at the point of reflection (an imaginary line)
Incident Ray – incoming ray of light
Reflected Ray – ray of light that bounces off an object
Angle of Incidence (θi) – angle between the incident ray
and the normal
Angle of Reflection (θr) – angle between the reflected ray
and the normal
Plane Mirrors
 is any mirror that has a flat reflective surface
 when you look in a plane mirror your image appears to
be as far behind the mirror as you are in front of it
 your image in a plane mirror is a virtual image
 virtual image – any image formed by rays that do not
come from the location of the image (if you place a
screen behind the mirror at the location of the image,
you will not be able to see the image on the screen)
 real image – light rays that create a real image actually
meet each other (can be placed on a screen)
 a mirror image is not an exact copy of the object it is
reflecting – it is a reverse of the image
Using Ray Diagrams to Predict the Images in Plane
Mirrors
1. From the top of the object, draw two incident rays
toward the mirror
2. Draw normals (point where incident ray hits) and
reflected rays (same angle as incident rays)
3. Use a similar procedure for the bottom of the object
4. To draw the image, you must make the reflected rays
meet. You must therefore extend them (with broken
lines) behind the mirror. Where the reflected rays
appear to come from is the location of the image
Usually the image distance equals the object distance
Diagram:
4 Characteristics of an Image
Size – is the image bigger, smaller, or the same size as the
object?
Attitude – is the image upright (same way up) or inverted
(upside down)?
Location – is the image in front of the mirror or behind it?
Type – is the image real or virtual?
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p. 486 #1-5
p. 493 # 2,3,5,6,7,11