Download Reflecting And Refracting Light

Wednesday, 02/12/15
TEKS:
P.7E Describe and predict
image formation as a
consequence of reflection from
a plane mirror and refraction
through a thin convex lens.
By the end of today,
IWBAT…
Essential Question:
Topic:
Light & Optics
What are Ray
Diagrams?
Analyze different wave
characteristics, including
reflection and refraction.
Reflecting And Refracting Light
Regular Reflection: Mirrors
Plane Mirrors: Flat Mirrors
Concave Mirrors: Mirrors
that are curved inward.
Convex Mirrors: Mirrors
that are curved outward.
Send rays straight back
Send rays inward
Send rays outward
Reflecting And Refracting Light
Regular Reflection: Mirrors
Plane Mirrors:
Convex Mirrors:
Concave Mirrors:
Reflecting And Refracting Light
Regular Reflection: Mirrors

Thicker media refracts light more.
Optics: the overall study of how light behaves

Geometric Optics focuses on the creation of
images. It is based on relationships between
angles and lines that describe light rays.
Reflection and Refraction



A lens is an optical device that is
used to bend light in a specific
way.
A converging lens bends light so
that the light rays come together
to a point.
A diverging lens bends light so it
spreads light apart instead of
coming together.
Reflection and Refraction


Mirrors reflect light, while prisms are optical devices that can
cause light to change directions.
A prism is a solid piece of glass with flat polished surfaces.
Reflection



Images appear in mirrors
because of how light is
reflected by mirrors.
The incident ray follows the
light falling onto the mirror.
The reflected ray follows
the light bouncing off the
mirror.
Reflection



In specular reflection each incident ray bounces off in a single
direction.
A surface that is not shiny creates diffuse reflection.
In diffuse reflection, a single ray of light scatters into many
directions.
Law of Reflection
The incident ray
strikes the mirror.
The reflected ray
bounces off.
The angle of
incidence equals
the angle of
reflection.
Law of Reflection


A light ray is incident on a
plane mirror with a 30
degree angle of incidence.
Sketch the incident and
reflected rays and determine
the angle of reflection.
30o
30o
Reflection
• We describe the path of light as straight-line rays
• Reflection off a flat surface follows a simple rule:
– angle in (incidence) equals angle out (reflection)
– angles measured from surface “normal” (perpendicular)
surface normal
incident ray
same
angle
exit ray
reflected ray
Reflection Vocabulary
• Real Image –
– Image is made from “real” light rays that
converge at a real focal point so the image
is REAL
– Can be projected onto a screen because
light actually passes through the point
where the image appears
– Always inverted
Reflection Vocabulary
• Virtual Image–
–“Not Real” because it cannot be
projected
–Image only seems to be there!