# Kennedy: MCQs in Amplitude Modulation

(Last Updated On: December 8, 2017)

This is the Multiple Choice Questions in Chapter 3: Amplitude Modulation from the book Electronic Communication Systems by George Kennedy. If you are looking for a reviewer in Communications Engineering this will definitely help. I can assure you that this will be a great help in reviewing the book in preparation for your Board Exam. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.

### Start Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. If the plate supply voltage for a plate-modulated class C amplifier is V, the maximum plate-cathode voltage could be almost as high as

• a. 4 V
• b. 3 V
• c. 2 V
• d. 1 V

2. In a low-level AM system, amplifiers following the modulated stage must be

• a. linear devices
• b. harmonic devices
• c. class C amplifiers
• d. nonlinear devices

3. If the carrier of a 100 percent modulated AM wave is suppressed, the percentage power saving will be

• a. 50
• b. 150
• c. 100
• d. 66.66

4. Leak-type bias is used in a plate-modulated class C amplifier to

• a. prevent tuned circuit damping
• b. prevent excessive grid current
• c. prevent overmodulation
• d. increase the bandwidth

5. The output stage of a television transmitter is most likely to be a

• a. plate-modulated class C amplifier
• b. grid-modulated class C amplifier
• c. screen-modulated class C amplifier
• d. grid-modulated class A amplifier

6. The modulation index of an AM wave is changed from 0 to 1. The transmitted power is

• a. unchanged
• b. halved
• c. doubled
• d. increase by 50 percent

7. One of the advantages of the base modulation over collector modulation of a transistor class C amplifier is

• a. the lower modulating power required
• b. higher power output per transistor
• c. better efficiency
• d. better linearity

8. A carrier is simultaneously modulated by two sine waves with modulation indices of 0.3 and 0.4; the total modulation index

• a. is 1
• b. cannot be calculated unless the phase relations are known
• c. is 0.5
• d. is 0.7

9. Amplitude modulation is used for broadcasting because

• a. it is more noise immune than other modulation systems.
• b. Compared with other systems it requires less transmitting power
• c. its use avoids receiver complexity.
• d. no other modulation system can provide the necessary bandwidth for high fidelity

10. What is the ratio of modulating power to total power at 100 percent modulation?

• a. 1:3
• b. 1:2
• c. 2:3
• d. None of the above