MM0704, Lesson 1
Lesson 1
RESONANCE AND TRANSIENCE
Task. The skills and knowledge taught in this lesson are common to all missile repairer tasks.
Objectives. When you have completed this lesson, you should be able to explain transience, waveforms, and time
constants for charging and discharging resistive-inductive circuits. You will also be able to explain the meaning of
resonance and the purpose, characteristics, operation, and use of series and parallel resonant circuits.
Conditions. You will have this subcourse book and work without supervision.
Standard. You must score at least 70 on the end-of-subcourse examination that covers this lesson and lessons 2, 3,
and 4 (answer 23 of the 30 questions correctly).
INTRODUCTION
In the analysis of AC circuits in the previous subcourse, you learned the characteristics of inductive and capacitive
reactance. When inductive and capacitive reactances are equal in magnitude, the circuit is said to be resonant. Since
the resonant circuit is sensitive to differences in frequency, it becomes important in many electronic devices where
frequency selection or rejection is required. Resonant circuits are used in electronics to determine the frequency of
operation of transmitters and receivers; in radio to allow selection of stations broadcasting on different frequencies; and
in telephone communication circuits to permit simultaneous transmission of dozens of conversations on a single line.
RESONANCE
Series
The series resonant circuit consists of capacitance and inductance in series. Resistances in the coil, condenser,
generator, and wiring are generally represented as one resistor in this type of circuit. This combination is possible
because resistances in series always add arithmetically.
The current and voltage conditions in a series resonant circuit are shown in figure 1-1 where equal inductive and
capacitive reactances are represented. This is a resonant circuit. Generally, the series resistance of such a circuit is
small compared with the reactance of the coil or the capacitor. In the circuit
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