PASCO AP-8586 Laser Speed of Light Apparatus - Manual (Page 6)

®
Model No. AP-8586 Laser Speed of Light System
5
Introduction
The velocity of light in free space is an important and intriguing
constant of nature. Whether the light comes from a laser on a desktop
or from a star that is hurling away at fantastic speeds, the velocity of
light will yield the same constant value. In more precise terminology,
the velocity of light is independent of the relative velocities of the light
source and the observer.
As Einstein first presented in his Special Theory of Relativity, the
speed of light is critically important in some surprising ways:
1. The velocity of light establishes an upper limit to the velocity that
may be imparted to any object.
2. Objects moving near the velocity of light follow a set of physical
laws drastically different, not only from Newton’s Laws, but from
the basic assumptions of human intuition.
It is not surprising that a great deal of time and effort has been invested
in measuring the speed of light. Some of the most accurate
measurements were made by Albert Michelson between 1926 and
1929. Michelson measured the velocity of light in air to be 2.99712 x
10
8
m/sec. From this result, he deduced the velocity in free space to be
2.99796 x 10
8
m/sec.
Equipment Setup
1. Stick four stainless steel strips to the front of the
receiver (Figure 1).
2. Mount the laser on its L-shaped bracket, with the
bracket bent away from the laser (Figure 2).
WARNING: Before
setting up your equipment,
please inform your students
of the hazards of lasers and
enforce appropriate safety
precautions in your
classroom. For more
information, see Appendix
C: Laser Safety in this
manual.
Figure 1:
Receiver
DIODE LASER
003-06157
AVOID EXPOSURE LASER LIGHT IS EMITTED FROM THIS APERTURE
OS-8528 DIODE LASER FOR
OPTICS SYSTEMS
Figure 2: Laser with bracket