List of top Physics Questions on communication systems

Find the correct combination of A, B, C and D inputs which can cause the LED to glow.

Identify the correct truth table of the given logic circuit.

Select correct truth table.

If the maximum and minimum amplitudes of an amplitude modulated wave are 9 V and 3 V respectively, then the modulation index is

If the frequencies of the carrier wave and message signal are $1$ MHz and $28$ kHz respectively, then the frequencies of the side bands are

The layer of the atmosphere which efficiently reflects high frequency waves particularly at night is

When the receiving antenna is on the ground, the range of a transmitting antenna of height 980 m is (Radius of the earth = 6400 km)

A sinusoidal carrier voltage is amplitude modulated The resultant amplitude modulated wave has maximum and minimum amplitude of $120 \, V$ and $80\, V$ respectively The amplitude of each sideband is:

Match List I with List II:

List I		List II
A.	Attenuation	I.	Combination of a receiver and transmitter
B.	Transducer	II.	Process of retrieval of information from the carrier wave at received
C.	Demodulation	III.	Converts one form of energy into another
D.	Repeater	IV.	Loss of strength of a signal while propagating through a medium

Choose the correct answer from the options given below :

A modulating signal is a square wave, as shown in the figure If the carrier wave is given as $c ( t )=2 \sin (8 \pi t)$ volts, the modulation index is:

A modulating signal is a square wave, as shown in the figure. If the carrier wave is given as c ( t )=2 sin (8 p t) volts, the modulation index is:

Which of the following frequencies does not belong to FM broadcast?

In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitude are found to be $6 V$ and $2 V$ respectively The modulation index is

If the height of the tower used for LOS communication is increased by 21%, the percentage change in range is?

If the height of the tower used for L.D.S is increased by 21% then percentage change in range is?

To radiate EM signal of wavelength \( \lambda \) with high efficiency, the antennas should have a minimum size equal to:

Height of the receiving and transmitting antenna in communication of a signal are 245 m and 180 m respectively. Find the maximum distance between the two antennas for proper communication.

The height of the antenna is 98 m. The radius of Earth is 6400 km. The area up to which it will transmit signal is:

In satellite communication, the uplink frequency band used is :

Match List I with List II

List I	List II
(A) Modulation	(III) Superimposition of a signal on a high frequency wave
(B) Baseband signals	(IV) Band of frequencies representing the original signal
(C) Demodulation	(I) Retrieval of information from the carrier wave at the receiver
(D) Bandwidth	(II) Frequency range over which an equipment operates

The required height of a TV tower which can cover the population of $603$ lakh is $h$ If the average population density is $100$ per square $km$ and the radius of earth is $6400\, km$, then the value of $h$ will be ______$m$

A transmitting antenna is kept on the surface of the earth. The minimum height of receiving antenna required to receive the signal in line of sight at 4 km distance from it is \( x \times 10^{-2} \) m. The value of \( x \) is:

Match List I with List I:

List I		List II
A	AM Broadcast	I	88-108 MHz
B	FM Broadcast	II	540-1600 kHz
C	Television	III	3.7-4.2 GHz
D	Satellite Communication	IV	54 MHz-890 MHz

Choose the correct answer from the options given below:

By what percentage will the transmission range of a TV tower be affected when the height of the tower is increased by 21% ?

A radio can tune to any station in $6\, MHz$ to $10\, MHz$ band The value of corresponding wavelength bandwidth will be :

In the case of amplitude modulation to avoid distortion the modulation index $(\mu)$ should be:

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