Learning objectives are stated at the beginning of each chapter. These learning objectives serve as a
preview of the information you are expected to learn in the chapter. The comprehensive check questions
are based on the objectives. By successfully completing the NRTC, you indicate that you have met the
objectives and have learned the information. The learning objectives are listed below.
Upon completion of this chapter, you should be able to:
1. State what wave motion is, define the terms reflection, refraction, and diffraction, and describe the
2. State what sound waves are and define a propagating medium.
3. List and define terms as applied to sound waves, such as cycle, frequency, wavelength, and
4. List the three requirements for sound.
5. Define pitch, intensity, loudness, and quality and their application to sound waves.
6. State the acoustical effects that echoes, reverberation, resonance, and noise have on sound waves.
7. Define light waves and list their characteristics.
8. List the various colors of light and define the terms reflection, refraction, diffusion, and absorption
as applied to light waves.
9. State the difference between sound waves and light waves.
10. State the electromagnetic wave theory and list the components of the electromagnetic wave.
INTRODUCTION TO WAVE PROPAGATION
Of the many technical subjects that naval personnel are expected to know, probably the one least
susceptible to change is the theory of wave propagation. The basic principles that enable waves to be
propagated (transmitted) through space are the same today as they were 70 years ago. One would think,
then, that a thorough understanding of these principles is a relatively simple task. For the electrical
engineer or the individual with a natural curiosity for the unknown, it is indeed a simple task. Most
technicians, however, tend to view wave propagation as something complex and confusing, and would
just as soon see this chapter completely disappear from training manuals. This attitude undoubtedly stems
from the fact that wave propagation is an invisible force that cannot be detected by the sense of sight or
touch. Understanding wave propagation requires the use of the imagination to visualize the associated
concepts and how they are used in practical application. This manual was developed to help you visualize