Name: ___________________________
Date: _____________________________
SNC 2D1 – Grade 10 Academic Science
LASER REFLECTION
Laser Reflection GIZMO
For years, the world's largest ground-based telescopes could generate only blurry
images of space, due to turbulence in Earth's atmosphere. Scientists have gotten around this
issue by sending telescopes into space beyond the effects of Earth's atmosphere. The largest
and best known of these telescopes is the Hubble Space Telescope.
Today, engineers in a field called adaptive optics have created mirrors for ground-based
telescopes that can be reshaped up to 100 times each second. This allows them to
compensate for distortion that the Earth's atmosphere causes. As a result, ground-based
telescopes can now "see" ten times better than before, and at a fraction of the cost of putting a
telescope in space.
USING GIZMOS: To begin, you must log into www.explorelearning.com
1. Click on Enroll in a Class
2. Enter CLASS CODE: AS4FJP27RA
3. Register if you do not already have a Gizmo account (no email address is required)
4. Launch Laser Gizmo and follow instructions below.
Reflection from an Ideal Mirror
In this activity, you will examine reflection from a plane mirror.
1. In the Gizmotm, select Ideal mirror from the dropdown menu. Be sure that Laser On/Off is
checked and all other options in the Gizmo are unchecked. What you see is a laser
beam striking a mirror and being reflected. The laser always comes in as a horizontal line.
The mirror can be angled, using the Angle slider.
a. Use the Angle slider to vary the angle of the mirror. Describe how the reflected beam
changes when the angle of the mirror increases or decreases.
b. Set the Angle of the mirror to 0 degrees. (To set a slider to a specific value, type the
number in the field to the right of the slider and hit Enter.) Describe the reflected laser
beam.
c. Describe the reflected beam when Angle is set to negative values.
Name: ___________________________
Date: _____________________________
SNC 2D1 – Grade 10 Academic Science
Laser Reflection GIZMO
d. Set the Angle to any value other than 0 degrees. Then grab the laser and drag it up and
down to different positions. How does this affect the reflected beam? How does it affect the
angle between the incoming beam and the reflected beam?
2. Set the Angle to 25 degrees and check Show normal. A normal line is perpendicular to a
plane from any viewpoint. Also shown are two angles, θI and θr. θI (theta i) refers to the
angle of incidence, the angle that the incoming ray makes with the normal. θr (theta r)
refers to the angle of reflection, the angle that the reflected ray makes with the normal.
a. How does the size of the angle of incidence compare with the size of the angle of
reflection?
b. Check Show protractor and Show center beam angles. What is the measure of the angle
of incidence? How about for the angle of reflection? Does this agree with your answer from
the preceding step?
c. How do the angle of incidence and the angle of reflection compare with the angle of the
mirror?
d. How does the angle formed by the incoming beam and the reflected beam compare with
the angle of the mirror?
3. Set the Angle to 30 degrees. Then check Insert beam splitter.
a. How do the seven incoming beams compare to one another? How do they compare to the
single beam that exists when the beam splitter is not present?
Name: ___________________________
Date: _____________________________
SNC 2D1 – Grade 10 Academic Science
b. How do the reflected beams compare to one another?
Laser Reflection GIZMO
c. Grab the laser and drag it up and down to several different positions. Describe the effect
that this has on the incoming beams and the reflected beams.
Reflection from Non-Ideal Mirrors
In this activity, you will examine reflection from some mirrors that are not perfect planes and,
based on that reflection, sketch the shape of the mirror.
1. From the dropdown menu, select Ideal mirror. Check Laser On/Off and Insert beam
splitter. All other options should be unchecked.
a. Set the Angle of the mirror to 0 degrees. Describe the appearance of the rays that are
reflected from the mirror.
b. Change the Angle to 20 degrees and describe the reflected rays.
2. Return the Angle to 0 degrees and select Mirror 1 from the dropdown menu. The surface
of this mirror is not a perfect plane (not perfectly flat and smooth). You will experiment to
find the angles on its surface at several locations.
a. Describe the appearance of the reflected rays. How do they compare to the reflected rays
from the ideal mirror? [
b. Uncheck Insert beam splitter and turn on Show protractor and Show angles. Then drag
the laser to its uppermost location, at Laser location = 35 cm. Describe the reflected ray
from this point on the mirror. What must be the angle of the spot on the mirror's surface
where this beam strikes it?
c. Slide the laser down to Laser position = 30 cm. Describe the reflected ray from this point
on the mirror. What must be the angle of the mirror's surface at this spot?
Name: ___________________________
SNC 2D1 – Grade 10 Academic Science
Date: _____________________________
Laser Reflection GIZMO
d. Continue moving the laser downward in 5 cm increments and determine the angle of the
surface of the mirror at each point. When you've gathered data for the entire range of the
laser's possible positions, use this data to sketch the shape of the surface of the mirror.
Laser Position
(cm)
Angle of Mirror’s
Surface
SKETCH
35
30
25
20
15
10
5
0
-5
-10
-15
-20
-25
-30
-35
3. Finally, take a look at Mirror 2 and Mirror 3 from the dropdown menu. By referring to your
results for Mirror 1 for assistance, what helps you predict the shape of a non-ideal mirror?
Why does using a ‘beam splitter’ aid in your investigation?