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1
MCQ (Single Correct Answer)

Three waves $A, B$ and $C$ of frequencies $1600 \mathrm{kHz}, 5 \mathrm{MHz}$ and 60 MHz , respectively are to be transmitted from one place to another. Which of the following is the most appropriate mode of communication?

A
$A$ is transmitted via space wave while $B$ and $C$ are transmitted via sky wave
B
$A$ is transmitted via ground wave, $B$ via sky wave and $C$ via space wave
C
$B$ and $C$ are transmitted via ground wave while $A$ is transmitted via sky wave
D
$B$ is transmitted via ground wave while $A$ and $C$ are transmitted via space wave
2
MCQ (Single Correct Answer)

A 100 m long antenna is mounted on a 500 m tall building. The complex can become a transmission tower for waves with $\lambda$

A
$\sim 400 \mathrm{~m}$
B
$\sim 25 \mathrm{~m}$
C
$\sim 150 \mathrm{~m}$
D
$\sim 2400 \mathrm{~m}$
3
MCQ (Single Correct Answer)

A 1 kW signal is transmitted using a communication channel which provides attenuation at the rate of -2 dB per km . If the communication channel has a total length of 5 km , the power of the signal received is [gain in $\mathrm{dB}=10 \log \left(\frac{P_0}{P_i}\right)$ ]

A
900 W
B
100 W
C
990 W
D
1010 W
4
MCQ (Single Correct Answer)

A speech signal of 3 kHz is used to modulate a carrier signal of frequency 1 MHz , using amplitude modulation. The frequencies of the side bands will be

A
1.003 MHz and 0.997 MHz
B
3001 kHz and 2997 kHz
C
1003 kHz and 1000 kHz
D
1 MHz and 0.997 MHz
5
MCQ (Single Correct Answer)

A message signal of frequency $\omega_m$ is superposed on a carrier wave of frequency $\omega_c$ to get an Amplitude Modulated Wave (AM). The frequency of the AM wave will be

A
$\omega_m$
B
$\omega_c$
C
$\frac{\omega_c+\omega_m}{2}$
D
$\frac{\omega_c-\omega_m}{2}$
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