Ray Model and Refletion note

Ray Model of Light and
Reflection
Light radiates in all directions from a
luminous object. Its direction of travel
can be represented by straight lines called
light rays.
Light rays
dna thgiL fo ledoM yaR
noitcelfeR
normal
in
ci
Light is 100% REFLECTED off of a mirror.
de
nt
ra
Angles are always measured relative to y
the normal
ra
When the mirror is flat, the light rays that
are reflected follow certain laws
ed
ct
le
ef
y
r
θi θr
reflecting surface
*copy the following diagram and laws......
Don't Copy
Predict where this light ray will reflect.
normal
Demos: Ball, laser, and/or string
Mirror terminology and laws (click below for laws)
point of incidence
First Law of Reflection:
­angle of incidence (θi) = angle of reflection (θr).
Second Law of Reflection:
­the incident ray, reflected ray and normal are all
in the same plane.
You will now do a 20 minute activity to prove
your prediction
normal
1. Draw this diagram using a ruler!
base
angle of angle of incidence reflection
4
2. Create this table
Trial #
3
2
1
angle of incidence angle of reflection
Hints: • make sure the rays all hit at the point of incidence
• work on the lab benches not on your desk
• use a sharp pencil
point of incidence
1
2. Place a mirror on the base line,
shine a light ray along each numbered
incident ray, and mark each reflected
ray with a numbered dot.
normal
3. Draw in the
reflected rays
beginning from the
point of incidence
each time.
3
2
Click just below centre each photo
Diffuse reflection
4. Complete your
table by measuring the
angles relative to the
normal.
Mirror
4
Specular reflection
http://canebrakecollections.com/index.php?main_page=index&cPath=1
Be sure to get the
definition of each.
1
http://www.sleep­ees.com/
5. Make a conclusion, clean up, show the teacher, sit down.
Practice..practice..practice.
Read p. 460­462
Answer p 462 #1­3
Do you want to see something really cool?
If yes then when I uncover this box stare at the 4 dots in the middle of the object for 1 minute and then look at something flat and white or light in colour.
2