Kids’ Career Day
Physics
February 13, 2010
Law of Reflection
1. Li
1
Line up your mirror
i
with
ith th
the
mirror in the drawing.
2. Li
2
Line up th
the ray off lilight
ht ffrom th
the fl
flash
h
light with one of the numbered lines in
the top half of the semicircle. You may
have to tilt the flash light a little to see the
ray on the paper.
Mirror
600
The number
Th
b near the
h line
li tells
ll you the
h
angle of incidence.
400
200
angle of
incidence
00
200
400
600
3. The light that has bounced off the
mirror is the reflected light. You may have
to tilt the flash light a little to see the
reflected ray on the paper.
paper
Find the line closest to the reflected ray.
The number near the line tells you the
angle of reflection.
Add the angle of reflection to the table
below.
angle of
incidence
4. The law of reflection states that
angle of
reflection
00
angle of incidence = angle of reflection
200
Do your observations agree with the
law of reflection?
400
600
If you want to see all of yourself in a mirror,
how tall must the mirror be?
Mirror
1. Line up your mirror with the mirror in the
drawing.
g
2. Point the flash light so that a light ray
starts from the shoe, bounces off the
mirror, and the reflected ray reaches the
eye of the woman.
Mark the spot where the light ray hits the
mirror with an “S” for shoe.
Trace the path of the light ray and draw a
line perpendicular to the mirror through S.
Can you find the angle of incidence and
the angle of reflection?
3. Point the flash light so that a light ray
starts from the hat, bounces off the mirror,
and the reflected ray reaches the eye of
the woman.
Mark the spot
p where the light
g ray
y hits the
mirror with an “H” for hat.
Trace the path of the light ray as before.
4. Measure the distance between the
marked points S and H and write the
answer in centimeters
centimeters. This is the
minimum mirror height.
5. Measure the height of the person, from
the shoes to the hat and write down the
value in centimeters.
6. If you know your height, can you now
predict how tall a mirror you need?
If you have questions about this after you get home, please contact me:
Jutta Luettmer-Strathmann, PhD, Physics Department, University of Akron, Akron, OH 44325-4001
jutta@uakron.edu