Modulation techniques (AM, FM, PM) MCQs

Electronics MCQs
  1. What is the purpose of modulation in communication systems?
    A. To eliminate noise from the signal
    B. To increase the frequency of the signal
    C. To encode information onto a carrier wave for transmission
    D. To amplify the transmitted signal

    Answer: C

  2. Which of the following is NOT a modulation technique?
    A. Amplitude Modulation (AM)
    B. Frequency Modulation (FM)
    C. Pulse Modulation (PM)
    D. Analog Multiplexing

    Answer: D

  3. In AM, the parameter of the carrier wave that is varied is:
    A. Frequency
    B. Amplitude
    C. Phase
    D. Wavelength

    Answer: B

  4. Which of the following is an application of AM?
    A. Satellite communication
    B. AM radio broadcasting
    C. Wi-Fi communication
    D. Mobile telephony

    Answer: B

  5. What is the bandwidth requirement for an AM signal with a maximum modulating frequency of 5 kHz?
    A. 5 kHz
    B. 10 kHz
    C. 15 kHz
    D. 20 kHz

    Answer: B

  6. Which term refers to the ratio of the amplitude of the modulating signal to the amplitude of the carrier signal?
    A. Modulation depth
    B. Modulation index
    C. Signal-to-noise ratio
    D. Bandwidth efficiency

    Answer: B

  7. In FM, the parameter of the carrier wave that is varied is:
    A. Amplitude
    B. Frequency
    C. Phase
    D. Wavelength

    Answer: B

  8. Which of the following is a primary advantage of FM over AM?
    A. Lower bandwidth requirement
    B. Better noise immunity
    C. Simpler demodulation
    D. Higher transmission power

    Answer: B

  9. What determines the bandwidth of an FM signal?
    A. The amplitude of the carrier wave
    B. The modulating signal frequency and amplitude
    C. The phase of the carrier wave
    D. The carrier frequency

    Answer: B

  10. FM is widely used in which of the following applications?
    A. AM radio broadcasting
    B. High-fidelity music transmission
    C. Morse code transmission
    D. Radar systems

    Answer: B

  11. In PM, the parameter of the carrier wave that is varied is:
    A. Frequency
    B. Amplitude
    C. Phase
    D. Wavelength

    Answer: C

  12. Phase modulation is closely related to which other modulation technique?
    A. Amplitude modulation (AM)
    B. Frequency modulation (FM)
    C. Pulse-code modulation (PCM)
    D. Quadrature amplitude modulation (QAM)

    Answer: B

  13. Which of the following is an application of phase modulation (PM)?
    A. AM radio
    B. GSM cellular communication
    C. Morse code transmission
    D. Optical fiber communication

    Answer: D

  14. Which modulation technique requires the largest bandwidth?
    A. AM
    B. FM
    C. PM
    D. All require the same bandwidth

    Answer: B

  15. Which modulation technique is least affected by noise?
    A. AM
    B. FM
    C. PM
    D. All are equally affected

    Answer: B

  16. In terms of complexity, which modulation scheme is the simplest to implement?
    A. AM
    B. FM
    C. PM
    D. All are equally complex

    Answer: A

  17. The process of recovering the original information signal from a modulated carrier is called:
    A. Encoding
    B. Demodulation
    C. Multiplexing
    D. Modulation

    Answer: B

  18. What is the modulation index for FM if the maximum frequency deviation is 50 kHz and the modulating frequency is 5 kHz?
    A. 5
    B. 10
    C. 50
    D. 500

    Answer: B

  19. In AM, the total power transmitted is split between the carrier and:
    A. Sidebands
    B. Noise
    C. Phase variation
    D. Harmonics

    Answer: A

  20. FM signals are demodulated using:
    A. Envelope detectors
    B. Frequency discriminators
    C. Phase-locked loops (PLL)
    D. Both B and C

    Answer: D

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