®
M o d e l N o . O S - 8 5 1 5 B
Ex p e r i m e n t 4 : S n e l l ’ s L a w
13
Experiment 4: Snell’s Law
Purpose
The purpose of this experiment is to determine the index
of refraction of the acrylic rhombus. For rays entering
the rhombus, you will measure the angles of incidence
and refraction and use Snell’s Law to calculate the index
of refraction.
Theory
For light crossing the boundary between two transparent
materials, Snell’s Law states
n
1
sin
θ
1
=
n
2
sin
θ
2
where
θ
1
is the angle of incidence,
θ
2
is the angle of
refraction, and
n
1
and
n
2
are the respective indices of
refraction of the materials (see Figure 4.1).
Procedure
1.
Place the light source in ray-box mode on a sheet of
white paper. Turn the wheel to select a single ray.
2.
Place the rhombus on the paper and position it so
the ray passes through the parallel sides as shown in
Figure 4.2.
3.
Mark the position of the parallel surfaces of the
rhombus and trace the incident and transmitted rays.
Indicate the incoming and the outgoing rays with arrows in the appropriate direc-
tions. Carefully mark where the rays enter and leave the rhombus.
4.
Remove the rhombus and draw a line on the paper connecting the points where
the rays entered and left the rhombus. This line represents the ray inside the
rhombus.
5.
Choose either the point where the ray enters the rhombus or the point where the
ray leaves the rhombus. At this point, draw the normal to the surface.
6.
Measure the angle of incidence (
θ
i
) and the angle of refraction with a protractor.
Both of these angles should be measured from the normal. Record the angles in
the first row of Table 4.1.
Required Equipment from Basic Optics System
Light Source
Rhombus from Ray Optics Kit
Other Required Equipment
Protractor
White paper
Normal to surface
Surface
Refracted ray
(
n
1
>
n
2
)
Incident ray
n
1
q
1
q
2
n
2
Figure 4.1
q
i
Incident ray
Figure 4.2
Summary of Contents for OS-8515B
Page 6: ... Basic Optics System About the Experiments 6 ...
Page 26: ... Basic Optics System Experiment 9 Apparent Depth 26 ...
Page 38: ... Basic Optics System Experiment 13 Telescope 38 ...
Page 42: ... Basic Optics System Experiment 14 Microscope 42 ...
Page 44: ... Basic Optics System Experiment 15 Shadows 44 ...
Page 46: ... Basic Optics System Telescope and Microscope Test Pattern 46 ...