# MCQ on Amplitude Modulation Pdf

Amplitude modulation : When amplitude of carrier wave is changed according to information signal is called amplitude modulation. e.g. All India Radio Mumbai (1044 KHz). Amplitude modulation is done by the electronic circuit called modulator. The amplitude of carrier modulator wave is not constant but it's envelope has similar sinusoidal variations as that of the modulating signal.

Solving MCQ questions of Amplitude modulation without any trouble is a very difficult task for each students. Most of the time they get stuck with a MCQ questions. In the below we provide MCQ on Amplitude modulation. students will find Multiple Choice Questions and Answers on Amplitude Modulation pdf.

## MCQ on Amplitude Modulation

1. Modulation is the phenomenon of___________

(a) superimposing the audio frequency signal Over a carrier wave

(b) separating the audio frequency signal from the carrier wave

(c) separating carier wave from the modulated wave

(d) any of 'a, 'b,c above

2. AM stands for______________

(a) Audio Modulation

(b) Amplitude Modulation

(c) Angle Modulation

(d) Antenna Modulation

3. Amplitude modulation is__________

(a) AM is Change in amplitude of the carrier according to modulating signal

(b) AM is Change in frequency of the carrier according to modulating signal

(c) Change in amplitude of the modulating signal according to carrier signal

(d) Change in amplitude of the carrier according to modulating signal frequency

4. In an AM wave useful power is carrier by ___________

(a) Carrier

(b) Sidebands

(c)  Both sidebands and carrier

(d) None of the above

5. The equation for full-carrier AM is_____________

(a) v(t) = (Ec + Em) x sin(ωct)

(b) v(t) = (Ec + Em) x sin(ωmt) + sin(ωct)

(c) v(t) = (Ec x Em) x sin(ωmt) x sin(ωct)

(d) v(t) = (Ec + Em sin(ωmt)) x sin(ωct)

6. The AM spectrum consists of__________

(a) Carrier frequency

(b) Upper side band frequency

(c) Lower side band frequency

(d) All of the above

7. In amplitude modulation, the bandwidth is________

(a) twice the audio signal frequency

(b) thrice the audio signal frequency

(c) thrice the carrier wave frequency

(d) twice the carrier wave frequency

8. Modulation is done in___________

(a) Transmitter

(d) None of the above

9. The ratio between the modulating signal voltage and the carrier voltage is called?

(a) Amplitude modulation

(b) Modulation frequency

(c) Modulation index

(d) Ratio of modulation

10. Two forms of angular modulation are_______

(a) phase modulation and frequency modulation

(b) phase modulation and amplitude modulation

(c) frequency modulation and amplitude modulation

(d) any of above

11. A 1000 kHz carrier is modulated with 800 Hz audio signals. What are the frequencies of first pair of the bands_________

(a) 1000.8 kHz, 999.2 kHz

(b) 999.2 kHz, 998.4 kHz

(c) 1001.6 kHz,1000.8 kHz

(d) 1000 kHz, 800 Hz

12. In A.M., the total modulation index should not exceed one or else_________

(a) the system will fail

(b) distortion will result

(c) amplifier will be damaged

(d) either a or c

13. In amplitude modulation________

(a) amplitude of carrier wave is varied about mean value

(b) angular frequency o is doubled

(c) angular frequency o is also varied

(d) amplitude of carrier wave is kept constant

14. Demodulation is the__________

(a) process of changing of modulating wave as the carrier wave

(b) process of coupling modulated wave with modulating wave

(c) process of separating carrier wave from the modulated wave

(d) process of combining the message signal with carrier wave

15. When there is no signal in AM, the amplitude or carrier is equal to______

(a) un modulated amplitude

(b) twice the carrier amplitude

(c) Modulating signal amplitude

(d) Twice the modulating signal amplitude

16. Which devices we use for AM demodulation________

(a) diode detector

(b) Transducer

(c) Both a and b

(d) none of these

17. Modulation is the phenomenon of____________

(a) superimposing the audio frequency signal over a carrier wave

(b) separating the audio frequency signal from the carrier wave

(c) separating carrier wave from the modulated wave

(d) any of (a), (b), (c) above

18. In AM, if modulation index is more than 100% then_________

(a) power of the wave increases

(b) efficiency of transmission increases

(c) wave get distorted

(d) band width increases

19.The modulation index of an over modulated wave is___________

(a) 1

(b) <1

(c) 0

(d) >1

20. The information which is transmitted by radiating the modified carrier waves is called___________

(a) communication

(b) modulated wave

(c) carrier wave

(d) transducers

21. The modulation can be done by________

(a) amplitude modulation

(b) frequency modulation

(c) both 'a' and 'b'

(d) either 'a' or 'b'

22. A modem acts as ........... in receiving mode______

(a) modulator

(c) demodulator

(b) transducer

(d) amplifire

23. Modulation index of an AM signal_____________

(a) depends upon peak amplitude of modulating signal

(b) depends upon peak amplitude of carrier and the modulating signal

(c) is a function of carrier frequency

(d) both 'a' and 'c

24. An audio signal in the frequency range of 20 Hz to 10 KHz modulates the carrier. The bandwidths requirement is__________

(a) 20 kHz

(b) 40 kHz

(c) cannot be determined from the data

(d) either 'a' or 'b'

25. In frequency modulation_______

(a) frequency of the carrier remains constant

(b) carrier frequency varies in accordance with the modulating signal frequency

(c) carrier frequency varies in accordance with the modulating signal amplitude

(d) both 'a' and 'b'

26. In a communication system, noise is most likely to affect the signal______

(a) at the transmitter

(b) in the transmission medium

(c) in the formation source

(d) at the detination

27. A demodulator______

(a) separates audio signal from modulated signal

(b) separates carrier signal from modulated signal

(c) passes the modulated signal without change

(d) either 'a' or b'

28. Modem is________

(a) a device to pass signal from one place to other as it is

(b) a device to rectify signal

(c) a contraction of the term modulation & demodulation

(d) either 'a' or 'b'

29. Carrier waves are_________

(a) high frequency waves

(b) low frequency waves

(c) information signal

(d) audio  waves

30. Amplitude of modulating signal is_________

(a) less than amplitude of carrier wave

(b) more than amplitude of carrier wave

(c) equal than amplitude of carrier wave

(d) kept double than amplitude of carrier wave

31. In modulation process, radio frequency wave is termed as_______
(a) modulating wave
(b) modulated wave
(d) EM wave
(c) carrier wave

32. 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 circuitry is simple
(d) no other modulation systems can provide the necessary bandwidth for high fidelity

33. The purpose of oscillator in the AM transmitter is to________
(a) provide modulating signal
(b) provide carrier
(c) provide enough power to meet transmission systems.
(d) both a and B

34. What do you mean by AM modulation?

(a) Vary the amplitude of the carrier as a function of the audio frequency.

(b) Vary the phase of the carrier depending on the audio signal.

(c) Vary the carrier frequency as a function of the audio frequency.

(d) All

35. In AM modulation if the modulation index is 1, the sum of the powers is the side bands is__________

a) Equal to the power of the carrier.

b) Equal to a quarter of the power of the carrier.

c) Equal to half the power of the carrier.

(d) None of the above

36. What is the time constant of a circuit that has a 220 capacitor microfarads and a 1 resistor in parallel?

a) 220 seconds.

b) 22 seconds.

c) 2.2 seconds.

(d) None of these

37.  In AM modulation the bandwidth is equal to:

a) Twice the audio frequency (2 Faf).

b) The audio frequency (Faf).

c) The attenuated carrier frequency 3 dB.

(d) None of these

38. In an AM wave useful power is carrier by___________

(a) Carrier

(b)Sidebands

(c) Both sidebands and carrier

(d) None of the above

39. An AM demodulator consists of_______

a) A diode to ground and a capacitor in series.

b) A diode of R.F. and a capacitor to ground.

c) A power supply type diode with a capacitor to ground.

(d) All