NCERT Solutions Class 12 Physics Chapter 15 Communication Systems

NCERT Solutions Class 12 Physics Chapter 15 Communication Systems have been provided below and is also available in Pdf for free download. The NCERT solutions for Class 12 Physics have been prepared as per the latest syllabus, NCERT books and examination pattern suggested in Class 12 by CBSE, NCERT and KVS. Questions given in NCERT book for Class 12 Physics are an important part of exams for Class 12 Physics and if answered properly can help you to get higher marks. Refer to more Chapter-wise answers for NCERT Class 12 Physics and also download more latest study material for all subjects. Chapter 15 Communication Systems is an important topic in Class 12, please refer to answers provided below to help you score better in exams

Chapter 15 Communication Systems Class 12 Physics NCERT Solutions

Class 12 Physics students should refer to the following NCERT questions with answers for Chapter 15 Communication Systems in Class 12. These NCERT Solutions with answers for Class 12 Physics will come in exams and help you to score good marks

Chapter 15 Communication Systems NCERT Solutions Class 12 Physics

Question. Which of the following frequencies will be suitable for beyond-the-horizon communication using sky waves? 
(a) 10 kHz
(b) 10 MHz
(c) 1 GHz
(d) 1000 GHz

Answer : B
For beyond-the-horizon communication, it is necessary for the signal waves to travel a large distance. 10 KHz signals cannot be radiated efficiently because of the antenna size. The high energy signal waves (1GHz − 1000 GHz) penetrate the ionosphere. 10 MHz frequencies get reflected easily from the ionosphere. Hence, signal waves of such frequencies are suitable for beyond-the-horizon communication.

Question. Frequencies in the UHF range normally propagate by means of:
(a) Ground waves.
(b) Sky waves.
(c) Surface waves.
(d) Space waves.

Answer : D
Owing to its high frequency, an ultra high frequency (UHF) wave can neither travel along the trajectory of the ground nor can it get reflected by the ionosphere. The signals having UHF are propagated through line-of-sight communication, which is nothing but space wave propagation.

Question. Digital signals
(i) Do not provide a continuous set of values,
(ii) Represent values as discrete steps,
(iii) Can utilize binary system, and
(iv) Can utilize decimal as well as binary systems.
Which of the above statements are true?
(a) (i) and (ii) only
(b) (ii) and (iii) only
(c) (i), (ii) and (iii) but not (iv)
(d) All of (i), (ii), (iii) and (iv).

Answer : C 
A digital signal uses the binary (0 and 1) system for transferring message signals. Such a system cannot utilise the decimal system (which corresponds to analogue signals). Digital signals represent discontinuous values.

Question. Is it necessary for a transmitting antenna to be at the same height as that of the receiving antenna for line-of-sight communication? A TV transmitting antenna is 81m tall. How much service area can it cover if the receiving antenna is at the ground level?
Answer : Line-of-sight communication means that there is no physical obstruction between the transmitter and the receiver. In such communications it is not necessary for the transmitting and receiving antennas to be at the same height.
Height of the given antenna, h = 81 m
Radius of earth, R = 6.4 × 106 m
For range, d = (2Rh)½, the service area of the antenna is given by the relation:
A = πd2 
= π (2Rh)
= 3.14 × 2 × 6.4 × 106 × 81
= 3255.55 × 106 m2
= 3255.55 
∼ 3256 km2

Question. A carrier wave of peak voltage 12 V is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of 75%?
Answer : Amplitude of the carrier wave, Ac = 12 V
Modulation index, m = 75% = 0.75
Amplitude of the modulating wave = Am
Using the relation for modulation index:
m = Am/Ac
∴Am = mAc
= 0.75 x 12 = gV

Question. A modulating signal is a square wave, as shown in Fig. 15.14.

""NCERT-Solutions-Class-12-Physics-Chapter-15-Communication-Systems-2

The carrier wave is given by: c(t) = 2 sin (8πt) volts.
(i) Sketch the amplitude modulated waveform
(ii) What is the modulation index?

Answer : It can be observed from the given modulating signal that the amplitude of the modulating signal, Am = 1 V
It is given that the carrier wave c (t) = 2 sin (8πt)
∴Amplitude of the carrier wave, Ac = 2 V
Time period of the modulating signal Tm = 1 s
The angular frequency of the modulating signal is calculated as:

""NCERT-Solutions-Class-12-Physics-Chapter-15-Communication-Systems-3

Question. For an amplitude modulated wave, the maximum amplitude is found to be 10 V while the minimum amplitude is found to be 2 V. Determine the modulation index μ. What would be the value of μ if the minimum amplitude is zero volt?
Answer : Maximum amplitude, Amax = 10 V
Minimum amplitude, Amin = 2 V
Modulation index μ, is given by the relation:

""NCERT-Solutions-Class-12-Physics-Chapter-15-Communication-Systems-1

Question. Due to economic reasons, only the upper sideband of an AM wave is transmitted, but at the receiving station, there is a facility for generating the carrier. Show that if a device is available which can multiply two signals, then it is possible to recover the modulating signal at the receiver station.
Answer : Let ωc and ωs be the respective frequencies of the carrier and signal waves.
Signal received at the receiving station, V = V1 cos (ωc + ωs)t
Instantaneous voltage of the carrier wave, Vin = Vc cos ωct

""NCERT-Solutions-Class-12-Physics-Chapter-15-Communication-Systems

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NCERT Solutions Class 12 Physics Chapter 15 Communication Systems

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Chapter 15 Communication Systems Class 12 Physics NCERT Solutions

The Class 12 Physics NCERT Solutions Chapter 15 Communication Systems are designed in a way that will help to improve the overall understanding of students. The answers to each question in Chapter 15 Communication Systems of Physics Class 12 has been designed based on the latest syllabus released for the current year. We have also provided detailed explanations for all difficult topics in Chapter 15 Communication Systems Class 12 chapter of Physics so that it can be easier for students to understand all answers.

NCERT Solutions Chapter 15 Communication Systems Class 12 Physics

Class 12 Physics NCERT Solutions Chapter 15 Communication Systems is a really good source using which the students can get more marks in exams. The same questions will be coming in your Class 12 Physics exam. Learn the Chapter 15 Communication Systems questions and answers daily to get a higher score. Chapter 15 Communication Systems of your Physics textbook has a lot of questions at the end of chapter to test the students understanding of the concepts taught in the chapter. Students have to solve the questions and refer to the step-by-step solutions provided by Physics teachers on studiestoday to get better problem-solving skills.

Chapter 15 Communication Systems Class 12 NCERT Solution Physics

These solutions of Chapter 15 Communication Systems NCERT Questions given in your textbook for Class 12 Physics have been designed to help students understand the difficult topics of Physics in an easy manner. These will also help to build a strong foundation in the Physics. There is a combination of theoretical and practical questions relating to all chapters in Physics to check the overall learning of the students of Class 12.

Class 12 NCERT Solution Physics Chapter 15 Communication Systems

NCERT Solutions Class 12 Physics Chapter 15 Communication Systems detailed answers are given with the objective of helping students compare their answers with the example. NCERT solutions for Class 12 Physics provide a strong foundation for every chapter. They ensure a smooth and easy knowledge of Revision notes for Class 12 Physics. As suggested by the HRD ministry, they will perform a major role in JEE. Students can easily download these solutions and use them to prepare for upcoming exams and also go through the Question Papers for Class 12 Physics to clarify all doubts

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