Modulation And Demodulation MCQ Questions & Answers

21

A 50 kW carrier is to be amplitude modulated to a level of 85%. What is the carrier power after modulation?

A) 50 kW B) 5 kW C) 8 kW D) 25 kW

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Answer & Solution

Answer: Option A

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22

The major advantage of FM over AM is ___________

A) Reception is less noisy B) Higher carrier frequency C) Smaller bandwidth D) Small frequency deviation

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Answer & Solution

Answer: Option A

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23

In an AM wave, the majority of the power is in ___________

A) Lower sideband B) Upper sideband C) Carrier D) None of the above

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Answer & Solution

Answer: Option C

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24

As the modulation level is increased, the carrier power ___________

A) Is increased B) Remains the same C) Is decreased D) None of the above

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Answer & Solution

Answer: Option B

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25

Modulation refers to a low-frequency signal controlling the ___________

A) Amplitude of the carrier B) Frequency of the carrier C) Phase of the carrier D) May be any of the above

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Answer & Solution

Answer: Option D

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26

In a radio receiver, noise is generally developed at ___________

A) IF stage B) Receiving antenna C) Audio stage D) RF stage

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Answer & Solution

Answer: Option D

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27

The diode detector in an AM radio receiver is usually found ___________

A) Before the first RF stage B) After the first RF stage C) After several stages of amplification D) None of the above

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Answer & Solution

Answer: Option C

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28

The function of ferrite antenna is to ___________

A) Reduce stray capacitance B) Stabilise d.c. bias C) Increase the Q of tuned circuit D) Reduce noise

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Answer & Solution

Answer: Option C

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29

If Amin = 40 and Amax = 60, what is the percentage of modulation?

A) 20% B) 40% C) 50% D) 10%

Discuss

Answer & Solution

Answer: Option A

Solution:

The correct answer is Option A: 20%.
Here's why:
Modulation percentage in Amplitude Modulation (AM) tells us how much the amplitude of the carrier signal changes.
It's calculated using the formula: Modulation Percentage = [(Amax - Amin) / (Amax + Amin)] * 100
Where:
Amax is the maximum amplitude of the modulated signal.
Amin is the minimum amplitude of the modulated signal.
In this problem:
Amax = 60
Amin = 40
So, let's plug in the values:
Modulation Percentage = [(60 - 40) / (60 + 40)] * 100
Modulation Percentage = [20 / 100] * 100
Modulation Percentage = 0.2 * 100
Modulation Percentage = 20%
Therefore, the percentage of modulation is 20%.

30

The signal voltage induced in the aerial of a radio receiver is of the order of ___________

A) mV B) µV C) V D) None of the above

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Answer & Solution

Answer: Option B

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Modulation And Demodulation MCQ Questions & Answers | Electrical Engineering