Unit 4 Optics: Properties of Light and Reflection SNC2D1 Grade
10 Science
Slide 2
Luminous objects Radiate light in all directions Represented by
a light ray on a diagram line & arrow shows direction light
waves travel in Light emitted from a source is called the incident
light
Slide 3
Light travels in a straight line as it is moving through the
same medium. Medium: the substance through which light travels
(air, water, glass, etc.)
Slide 4
Light determines a property of matter, depending on how it
strikes it. Matter can be classified into 3 categories:
Transparent: material that transmits all incident light; objects
are seen through the material.
Slide 5
Translucent: material that transmits some incident light but
absorbs or reflects the rest; objects are not clearly seen through
the material. Opaque: material does not transmit any incident
light; all incident light is either absorbed or reflected. Object
behind the material can not be seen.
Slide 6
Shadows Opaque objects will not allow light to pass through,
and therefore cast a shadow, outlining the edge of the object with
light
Slide 7
Umbra: Darkest part of the shadow Penumbra: Region where some
or all of the light source is obscured
Slide 8
Slide 9
Reflection the change in direction of a wave when it reaches a
surface and bounces off that surface.
Slide 10
Reflection Specular (Regular): reflection off a smooth, shiny
surface E.g. plane mirror, still water Diffuse: reflection of light
off a irregular or dull surface
Slide 11
A mirror Any polished surface that exhibits reflection. 2
parts: front = sheet of glass back = thin layer of reflective
silver or aluminum An image: reproduction of an original object
through the use of light
Slide 12
Mirrors object image It is possible to see images in
mirrors.
Slide 13
Reflection (bouncing light) Reflection is when light changes
direction by bouncing off a surface. When light is reflected off a
mirror, it hits the mirror at the same angle (the incidence angle,
i ) as it reflects off the mirror (the reflection angle, r ). The
normal is an imaginary line which lies at right angles to the
mirror where the ray hits it. rr ii Mirror normal incident ray
reflected ray
Slide 14
The Laws of Reflection 1. The angle of incidence = The angle of
reflection 2. The incident ray, reflected ray, and the normal all
lie in the same plane. Lets draw our own ray diagram!
Slide 15
Ray diagrams
Slide 16
Mirrors reflect light rays.
Slide 17
Images in Plane Mirrors Images seen in mirrors are VIRTUAL
IMAGES An image in which light does not actually arrive at or come
from the image location This light only appears to come from the
image That is why we see the image in or behind the mirror
Slide 18
Images in Plane Mirrors (flat mirrors) How do we see images in
mirrors?
Slide 19
Images in Plane Mirrors (flat mirrors) objectimage Light
reflected off the mirror converges to form an image in the eye. How
do we see images in mirrors?
Slide 20
Images in Plane Mirrors (flat mirrors) objectimage Light
reflected off the mirror converges to form an image in the eye. The
eye perceives light rays as if they came through the mirror.
Imaginary light rays extended behind mirrors are called sight
lines. How do we see images in mirrors?
Slide 21
Images in Plane Mirrors (flat mirrors) objectimage Light
reflected off the mirror converges to form an image in the eye. The
eye perceives light rays as if they came through the mirror.
Imaginary light rays extended behind mirrors are called sight
lines. The image is virtual since it is formed by imaginary sight
lines, not real light rays. How do we see images in mirrors?
Slide 22
Slide 23
SALT is used to describe images formed by mirrors. 1. S- Size:
compared to original object is it same size, smaller or bigger? 2.
A- Attitude: which way the image is oriented compared to the
original object (upright or inverted). 3. L- Location: location of
the image (in front or behind the mirror). 4. T- Type: is the image
a real image or virtual image? S.A.L.T
Slide 24
1. S same as object 2. A upright 3. L behind mirror 4. T
virtual Characteristics of a plane mirror image:
Slide 25
The image in a plane mirror appears to be backwards compared to
how we view the object directly. This is why the word on the front
of an AMBULANCE is written backwards- so it can be read when seen
in a rear-view mirror.