EXTENSION COURSE OF THE US ARMY SIGNAL SCHOOL
LESSON SOLUTIONS
SIGNAL SUBCOURSE 333......................... Telephone System Characteristics
LESSON 1 ..................................... Introduction to Telephone Systems
1. b--para 5, fig. 3
2. a--para 6b, c; 7
3. b--para 10c
4. a--Appendix B, para 6b
5. a--para l0b
6. e--para 12a
74 x 20 = 1,480 ohms
7. b--para 14c
8. a--para 28a(6), (7); fig. 15
9. d--tables I, II; Appendix B, para 2a, b
When XL is equal to XC, the impedance is nearly equal to R. Tables I and
II of Appendix A show that when F = 2,000 Hz, L = 0.006 henry and C = 0.000001
farad; XL = 75.4 ohms and XC = 79 ohms. Since the reactances are nearly equal,
the circuit is largely resistive at approximately 2,000 Hz.
The circuit
impedance is therefore approximately equal to the value of R (157 ohm).
10. a--Appendix B, para 2
11. a--Appendix B, para 3, 5
12. a--para 8b; Appendix B, para 6b
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