Experiment 26
Reflection and Refraction
Advanced Reading:
(Serway) Chapter 35, sections 35-4,
35-5 & 35-8.
Equipment:
1 Plexi-Ray set (includes plane mirror,
plastic prism, pins)
1 cork board
1 protractor
1 30 cm ruler
Objective:
The object of this experiment is to
study the laws of reflection and
refraction.
Theory:
The Law of Reflection states that
the angle of incident ray equals the
angle of the reflected ray, or θi = θR
The Law of Refraction (Snell's
Law) relates how a ray of light will
behave when passing from one media
to the other. It is given by:
n1sinθi = n2 sinθ r
where n1 and n2 are the indices of
refraction for the two different media.
Figures 23-2 and 23-3 (note- figure
labeling is off, but correct) state these
two laws pictorially.
Procedure:
Part 1: Reflection
1. Draw a line approximately 20 cm
long at the center of a sheet of clean,
white paper. This will be the baseline.
Draw another line normal (normal =
90
o) to the first line using the
protractor. Place the plane mirror into
the slots of the little pieces of cork in
the Plexi-Ray kit so that it will stand-
up. Next, place the mirror so that the
back (the reflecting surface) is on the
first line.
figure 26 -1
N
ri
Figure 23-2
Reflection from a plane mirror
N
n1
n2
i
r
Figure 23-3
Refraction when changing media
2. Draw a ray on the left side of the
normal line as you face the mirror that
is at least 20 cm long from the point
where the normal line joins the
baseline. Stick two pins vertically on
the line, one approximately 20 cm and
the other at approximately 10 cm from
the mirror along the line. Label these
