Hertz and Resonant Circuit

1. A technique for resolving complex repetitive waveforms into sine or cosine waves and a dc component is known as:

a) Harmonic Analysis
b) Armstrong’s Principle
c) Fourier Analysis
d) Frequency Analysis

Answer: c

2. The statement “information is proportional to bandwidth” is known as:

a) Simpson Rule
b) Shannon’s Law.
c) Fourier’s Law.
d) Hartley’s Law

Answer: d

3. Given that a filter has a Q of 50 and a BW of 500 Hz, determine its resonant or center frequency.

a) 100 kHz
b) 25,000 kHz
c) 2500 kHz
d) 250 kHz

Answer: b

4. A device that converts energy from one form to another is called a:

a) transducer.
b) transmitter.
c) modulator.
d) detector.

Answer: a

5. The device which extracts the information signal from the high frequency carrier in a receiver is called a:

a) transducer.
b) transmitter.
c) modulator.
d) demodulator.

Answer: d

6. Frequencies between 3 and 30 Mhz are referred to as:

a. Ultra-High Frequencies (UHF’).
b. High Frequencies (HF).
c. Very-High Frequencies (VHF’).
d. Medium Frequencies (MF).

Answer: b

7. Ultra-High Frequency signals are between:

a) 30 Mhz and 300 MHz.
b) 3 Mhz and 30 GHz.
c) 3 Mhz and 30 MHz.
d) 300 Mhz and 3 GHz.

Answer: d

8. Hartley’s law states that:

a) bandwidth is directly proportional to both the amount of information and time of transmission.

b) the amount of information is directly proportional to both the system bandwidth and time of transmission.

c) the time of transmission is directly proportional to both the system bandwidth and the amount of information.

d) the bandwidth is directly proportional to both the amount of information and the amount of noise present.

Answer: b

9. A ramp waveform of the type shown in Figure 1-la has a peak-to-peak amplitude of 2V and a frequency of 50 Hz. The term representing the fifth harmonic has a coefficient of

a) 0.2
b) 2.5
c) 0.127
d) 0.254

Answer: c

10. A square wave of the type shown in Figure 1-lc has a peak-to-peak amplitude of 10V and a frequency of 200 Hz. The term representing the fifth harmonic is approximately:

a. 1.27 sin 6283t

b. 0.2 sin 6283t
c. 4 sin 3142t
d. 6.35 sin 6283t

Answer: a

11. A 4.7 mH inductor has a Q of 3500 at a frequency of 50 MHz. Its internal resistance is approximately:

a) 422 ohms.
b) 67.14 ohms.
c) 14.9 milliohms.
d) 2.37 milliohms.

Answer: a

12. The resonant frequency of the resonant circuit given in Figure 1-2 is:

a) 129 kHz.
b) 41.1 kHz.
c) 20.6 kHz.
d) 2.65GHz.

Answer: c

13. The impedance of the resonant circuit given in Figure 1-2 is:

a) 1553 ohms.
b) 2053 ohms.
c) 500 ohms.
d) 1632 ohms.

Answer: c

14. The bandwidth of the resonant circuit given in Figure 1-2 is:

a) 1.59 x 10’° Hz.
b) 2.4 X 106 Hz.
c) 41.6 X 103 Hz.
d) 6635 Hz.

Answer: d

15. The parallel resonant circuit of Figure 1-3 has a resonant frequency of approximately:

a) 259 kHz
b) 10.7 GHz
c) 41.3 kHz
d) 82.6 kHz

Answer: c

16. The parallel resonant circuit of Figure 1-3 has Q and BW equal to:

a) 233 and 176. Hz, respectively
b) 233 and 241 Hz, respectively
c) 1111 and 37.2 Hz, respectively
d) 171.2 and 241 Hz, respectively

Answer: a

17. The maximum impedance at the resonant frequency for the circuit of Figure 1-3 is approximately:

a) 10.8 kilo-ohms
b) 1.165 kilo-ohms
c) 5.825 kilo-ohms
d) 271.4 kilo-ohms

Answer: d

18. A measured value of 10mW will result in what dBm power level?

a) 0dBm
b) 3dBm
c) 10dBm
d) –3dBm

Answer: c

19. Determine the voltage level required to produce a +10dBm level. Assume a 600Ω system.

a) 1.947V
b) 2.45V
c) .775V
d) none of the above

Answer: b

20. Convert 300W to dBW.

a) 54.77 dBW
b) –24.77 dBW
c) –10.0 dBW
d) 24.77 dBW

Answer: d

21. A laser diode outputs +8 dBm. Convert this value to Watts.

a) 0.0063W
b) 0.063W
c) 0.63W
d) 0.00063W

Answer: a

22. A square wave is made up of a summation of:

a) ramps
b) sinusoids
c) rectangle waves
d) pulses

Answer: b

23. Figure 1-5 was obtained from a DSO. What are the frequencies of the third and fifth harmonics?

a) 12.5 and 25kHz
b) 37.5 and 62.5 kHz
c) 10 and 20 kHz
d) 30 and 50 kHz

Answer: b