Radar and Sonar William C. Vergara Sometimes, when conditions
are right, you can hear your own echo. If you shout "hello," the
sound may bounce back at you from a large object. You then hear
your own voice coming back. Your returning voice is called an
echo. Radar and sonar are electronic devices that use the
principle of an echo to detect and locate objects. Both radar
and sonar locate objects from the echo of a signal that is
bounced off the object. Radar uses radio waves, which are a type
of electromagnetic energy. Sonar uses the echo principle by
sending out sound waves underwater or through the human body to
locate objects. Sound waves are a type of acoustic energy.
Because of the different type of energy used in radar and sonar,
each has its own applications. The word "radar" was formed from
the first letters of the term "radio detection and ranging." A
radio wave is a type of electromagnetic radiation. (Microwaves,
X-rays, and light waves are other types.) It is the fundamental
part of this form of tec