Lesson 1 Sound and Telephony

Local-Battery Telephone Principles
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LESSON 1

SOUND AND TELEPHONY

CREDIT HOURS .......................................................... 2

TEXT ASSIGNMENT ................................................... TM 11-678, para 1-30

MATERIALS REQUIRED ............................................ None

LESSON OBJECTIVE .................................................. To familiarize you with the principles, characteristics,

and transmission of sound and the construction and

functions of the telephone transmitter and receiver.

SUGGESTIONS ............................................................ Miniaturization and synthetics have changed

the

physical appearance of some of the telephones

and

telephone components illustrated in some figures of

11-678.

However, the electrical circuits and

the

functions performed remain unchanged.

SPECIAL NOTE

Cycles per second (cps) is the unit of frequency. Texts often express the frequency only in cycles. However,

the National Bureau of Standards has adopted the unit hertz (Hz) to replace cycles per second as the unit of

frequency. Thus, 1 Hz - 1 cps.

LESSON EXERCISES

In each of the following exercises, select the ONE answer that BEST completes the statement or answers the

question. Indicate your solution by circling the letter opposite the correct answer in the subcourse booklet.

1. The limitation to communication imposed by distance was practically eliminated by the invention of the

telephone. The telephone system conquers distance by

a. transmitting the actual voice of the speaker to a receiver.

b. amplifying the sound waves and transmitting them over wires.

410 L1