R4RIN – MCQs, Mock Tests | NCERT Class 12 MCQ Questions for Class 12 Physics Chapter 15 Communication Systems

Who undertook the first space walk and in which year?

1. Leonov 1965
2. Neil Armstrong, 1969
3. Rakesh Sharma. 1998
4. None of the above these

✅ Correct Answer: 1

The term used “to collect the information about an object and a place without physical contact” is called :

1. modulation
2. communication
3. amplification
4. remote sensing

✅ Correct Answer: 4

The audio frequencies range from:

1. 20 Hz to 20.000 kHz
2. 20 Hz to 20 kHz
3. 20 kHz to 20.000 kHz
4. None of the these

✅ Correct Answer: 2

The wavelength of a wave of frequency 10 kHz is:

1. 30 m
2. 300 m
3. 30 km
4. 300 km

✅ Correct Answer: 3

Which of the following is not transducer?

1. Loudspeaker
2. Amplifier
3. Microphone
4. All

✅ Correct Answer: 2

The space waves which are affected seriously by atmospheric conditions are:

1. MF
2. HUF
3. VHF
4. UHF

✅ Correct Answer: 4

An antenna is:

1. Inductive
2. Capacitive
3. Resistive
4. A transformer

✅ Correct Answer: 1

Broadcasting antenna are generally:

1. Ommi directional type
2. Vertical type
3. Horizontal type
4. None

✅ Correct Answer: 2

The modulation index in amplitude modulation is:

1. Always zero
2. Between 0 and 1
3. Between 1 and ∞
4. None of these

✅ Correct Answer: 3

The output of a digital computer is an example of:

1. digital signal
2. analog signal
3. both (a) and (b)
4. neither (a) nor (b)

✅ Correct Answer: 1

Name the man who was first to place his foot on the moon and in which year:

1. Neil Armstrong, 1969
2. James Van A lien, 1971
3. Leonov, 1965
4. None of the these

✅ Correct Answer: 1

A microphone converts:

1. sound signals into electrical signals
2. electrical signals into sound signals
3. both (a) and (b)
4. Neither (a) nor (b)

✅ Correct Answer: 1

A loudspeaker converts:

1. electrical signals into sound signals
2. sound signals into electrical signals
3. both (a) and (b)
4. neither (a) nor (b)

✅ Correct Answer: 1

The length of a half wave dipole at 30 mega-hertz is:

1. 5 m
2. 10 m
3. 25 m
4. 80 m

✅ Correct Answer: 1

In space communication, the sound waves can be sent from one place to another:

1. through space
2. through wires
3. by superimposing it on undamped electro-magnetic waves
4. by superimposing it on damped electro-magnetic waves

✅ Correct Answer: 3

Which is more advantageous?

1. analog data communication
2. digital data communication
3. both (a) and (b) are equally good
4. depends on the situation

✅ Correct Answer: 2

Communication channel consists of:

1. transmission line only
2. optical fibre only
3. free space only
4. All the above

✅ Correct Answer: 4

AM is used for broadcasting because:

1. it is more noise immune than other modulation system
2. it requires less transmitting power compare with other systems
3. its use avoids receiver complexity
4. No other modulation system can provide the necessary bandwidth faithful transmission

✅ Correct Answer: 3

Digital signals:

1. represents values as discrete steps
2. Do not represents values as discrete steps
3. represent values steps
4. represent random steps

✅ Correct Answer: 1

Increase in frequency deviation results into:

1. increase in noise of FM receiver
2. decrease in noise of AM receiver
3. increase in noise of Am receiver
4. decrease in noise of FM receiver

✅ Correct Answer: 2