# NEET > Communication System

Explore popular questions from Communication System for NEET. This collection covers Communication System previous year NEET questions hand picked by popular teachers.

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Q 1.

Correct4

Incorrect-1

Communication is the process of

A

keeping in touch

exchange information

C

D

entertainment by electronics

##### Explanation

Q 2.

Correct4

Incorrect-1

Which of the following is the element of a communication system?

A

Transmitter

B

channel

C

All of the above

##### Explanation

Q 3.

Correct4

Incorrect-1

A transducer used at the transmitting end, serves the purpose of converting

A

electrical signal to sound form

sound signal to electrical form

C

electrical signal to magnetic form

D

sound signal to magnetic form

##### Explanation

Q 4.

Correct4

Incorrect-1

The term channel is used to indicate

A

the amplitude range allocated to a given source

the frequency range allocated to a given source

C

the voltage-range allocated to a given source

D

All of the above

##### Explanation

Q 5.

Correct4

Incorrect-1

Buffer amplifier is used at the transmitting end to

A

feed carrier frequency to master oscillator

B

amplify carrier frequency

C

mix modulating signal with carrier frequency

isolate master oscillator from other stages of transmitter.

##### Explanation

Q 6.

Correct4

Incorrect-1

The purpose of a detector at the receiving end is

A

to amplify signal

B

to reduce its frequency level

C

to modulate signal

to demodulate signal

##### Explanation

Q 7.

Correct4

Incorrect-1

Modem is a short form of

modulator-demodulator

B

multiplexer-demultiplexer

C

multivibrator-degenerator

D

None of these

##### Explanation

Q 8.

Correct4

Incorrect-1

Ground wave propagation is possible for

low radio frequency over a short range

B

high radio frequency over a short range

C

high radio frequency over a long range

D

low radio frequency over a short range.

##### Explanation

Q 9.

Correct4

Incorrect-1

Long range transmission of TV-signal is done by

A

space-wave

B

sky waves

C

ground wave

artificial satellite.

##### Explanation

Q 10.

Correct4

Incorrect-1

Field strength of tropospheric TV signal is proportional to

{tex} \frac { 1 } { \lambda } {/tex}

B

{tex} \lambda {/tex}

C

{tex} \frac { 1 } { \lambda ^ { 2 } } {/tex}

D

{tex} \lambda ^ { 2 } {/tex}

##### Explanation

Q 11.

Correct4

Incorrect-1

Long range propagation is not possible by space wave propagation because

height of troposhere is quite small

B

height of troposhere is large

C

troposphere absorbs transmitted wave

D

None of these

##### Explanation

Q 12.

Correct4

Incorrect-1

Critical frequency that gets reflected back from ionosphere is

A

same for all layers of the ionosphere

different for different layers of the ionosphere

C

not dependent on layers of the ionosphere

D

None of these

##### Explanation

Q 13.

Correct4

Incorrect-1

Encoding of signal is required for

modulation at transmitting end

B

modulation at receiving end

C

demodulation at receiving end

D

demodulation at transmitting end

##### Explanation

Q 14.

Correct4

Incorrect-1

Communication on ground is through electromagnetic waves of wavelength

A

larger than {tex} 600 \mathrm { m } {/tex}

B

between {tex}200{/tex} and {tex} 600 \mathrm { m } {/tex}

C

between {tex}1{/tex} and {tex} 5 \mathrm { m } {/tex}

between {tex} 10 ^ { - 3 } {/tex} and {tex}0.1{/tex}

##### Explanation

Q 15.

Correct4

Incorrect-1

During ground wave propagation the transmitted waves gets attenuated because

A

earth surface absorbs the waves

B

frequency of the waves are too low

C

energy content of these waves are high

earth surface offers resistance.

##### Explanation

Q 16.

Correct4

Incorrect-1

Wave obtained on superimposition of audible frequency e.m. wave is known as

A

carrier wave

B

high frequency wave

C

modulating wave

modulated wave

##### Explanation

Q 17.

Correct4

Incorrect-1

The AM wave is equivalent to the summation of

A

two sinusoidal waves

three sinusoidal waves

C

four sinusoidal waves

D

None of these

##### Explanation

Q 18.

Correct4

Incorrect-1

Frequencies of sideband is

{tex} 2.50005 \times 10 ^ { 6 } \mathrm { Hz } , 2.49995 \times 10 ^ { 6 } \mathrm { Hz } {/tex}

B

{tex} 2.505 \times 10 ^ { 6 } \mathrm { Hz } , 2.495 \times 10 ^ { 6 } \mathrm { Hz } {/tex}

C

{tex} 2.505 \times 10 ^ { 6 } \mathrm { kHz } , 2.495 \times 10 ^ { 6 } \mathrm { kHz } {/tex}

D

{tex} 2.505 \mathrm { MHz } , 2.495 \mathrm { kHz } {/tex}

##### Explanation

Q 19.

Correct4

Incorrect-1

The process of superimposing signal frequency (i.e, audio wave) on the carrier wave is known as

A

Transmission

B

Reception

Modulation

D

Detection

##### Explanation

Q 20.

Correct4

Incorrect-1

As the height of satellite orbit gets lower, the speed of the satellite

A

increases

decreases

C

remain same

D

both (a) and (b)

##### Explanation

Q 21.

Correct4

Incorrect-1

Which of the following is drawback of amplitude modulation?

A

low efficiency

B

noise reception

C

operating range is small

all of these

##### Explanation

Q 22.

Correct4

Incorrect-1

What is the modulation index of an over modulated wave

A

1

B

Zero

C

< 1

> 1

##### Explanation

Q 23.

Correct4

Incorrect-1

The maximum line-of-sight distance d{tex}_ \mathrm{M}{/tex} between two antennas having heights {tex} \mathrm { h } _ { \mathrm { T } } {/tex} and {tex} \mathrm { h } _ { \mathrm { R } } {/tex} above the earth is

A

{tex} \sqrt { \mathrm { R } \left( \mathrm { h } _ { \mathrm { T } } + \mathrm { h } _ { \mathrm { R } } \right) } {/tex}

B

{tex} \sqrt { 2 \mathrm { R } / \left( \mathrm { h } _ { \mathrm { T } } + \mathrm { h } _ { \mathrm { R } } \right) } {/tex}

C

{tex} \sqrt { \mathrm { Rh } _ { \mathrm { T } } } + \sqrt { 2 \mathrm { Rh } _ { \mathrm { R } } } {/tex}

{tex} \sqrt { 2 \mathrm { Rh } _ { \mathrm { T } } } + \sqrt { 2 \mathrm { Rh } _ { \mathrm { R } } } {/tex}

##### Explanation

Q 24.

Correct4

Incorrect-1

In AM waves, the amplitude of each side band frequency is

A

{tex} E _ { c } {/tex}

B

{tex} \mathrm { mE } _ { \mathrm { c } } {/tex}

{tex} \frac { m E _ { c } } { 2 } {/tex}

D

{tex} 2 \mathrm { mE } {/tex}

##### Explanation

Q 25.

Correct4

Incorrect-1

For good demodulation of AM signal of carrier frequency {tex} f , {/tex} the value of {tex} \mathrm { RC } {/tex} should be

A

{tex} R C = \frac { 1 } { f } {/tex}

B

{tex} R C < \frac { 1 } { f } {/tex}

C

{tex} R C \geq \frac { 1 } { f } {/tex}

{tex} R C > > \frac { 1 } { f } {/tex}