# Amplitude Modulation and Modulation Index MCQ’s

This set of Avionics Multiple Choice Questions & Answers (MCQs) focuses on “Amplitude Modulation and Modulation Index”.

1. What is the line connecting the positive and negative peaks of the carrier waveform called?
a) Peak line
b) Maximum amplitude ceiling
c) Modulation index
d) Envelope

2. What is the reference line for the modulating signal?
a) Zero line
b) Carrier peak line
c) Modulated peak line
d) Un-modulated peak line

3. In Amplitude Modulation, the instantaneous values of the carrier amplitude changes in accordance with the amplitude and frequency variations of the modulating signal.
a) True
b) False

4. What happens when the amplitude of the modulating signal is greater than the amplitude of the carrier?
a) Decay
b) Distortion
c) Amplification
d) Attenuation

5. What is the circuit used for producing AM called?
a) Modulator
b) Transmitter
d) Duplexer

6. What is the percentage of modulation if the modulating signal is of 7.5V and carrier is of 9V?
a) 100
b) 91
c) 83.33
d) 0

7. What is the effect of distortion?
a) Total information loss
b) Error information
c) Attenuated information
d) Amplified information

8. 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

9. When does over-modulation occur?
a) Modulating signal voltage < Carrier voltage
b) Modulating signal voltage > Carrier voltage
c) Modulating signal voltage = Carrier voltage
d) Modulating signal voltage =0

10. What is the modulating signal voltage if the maximum and the minimum voltages on the wave was observed to be 5.9v and 1.2v respectively?
a) 2.35v
b) 2.12v
c) 1.85v
d) 3.21v

11. What is the condition for greatest output power at the transmitter without distortion?
a) Modulating signal voltage > Carrier voltage
b) Modulating signal voltage < Carrier voltage
c) Modulating signal voltage = Carrier voltage
d) Modulating signal voltage = 0

12. What is the modulation index value if Vmax=5.9v and Vmin=1.2v?
a) 0.5
b) 0.662
c) 0.425
d) 0.14

13. Which of the following modulating signal voltage would cause over-modulation on a carrier voltage of 10v?
a) 9.5
b) 9.99
c) 10
d) 12 5 Star
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