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# NCERT solutions for Class 12 Physics chapter 15 - Communication Systems

## Chapter 15 - Communication Systems

#### Pages 530 - 531

Q 1 | Page 530

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

Q 2 | Page 530

Frequencies in the UHF range normally propagate by means of:

(a) Ground waves.

(b) Sky waves.

(c) Surface waves.

(d) Space waves.

Q 3 | Page 530

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).

Q 4 | Page 530

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?

Q 5 | Page 530

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%?

Q 6 | Page 530

A modulating signal is a square wave, as shown

The carrier wave is given by  c(t) = 2 sin (8pit) "volts"

(i) Sketch the amplitude modulated waveform

(ii) What is the modulation index?

Q 7 | Page 531

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?

Q 8 | Page 531

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.

## NCERT solutions for Class 12 Physics chapter 15 - Communication Systems

NCERT solutions for Class 12 Physics chapter 15 (Communication Systems) include all questions with solution and detail explanation from Physics Textbook for Class 12 Part 2. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has created the CBSE Physics Textbook for Class 12 Part 2 solutions in a manner that help students grasp basic concepts better and faster.

Further, we at shaalaa.com are providing such solutions so that students can prepare for written exams. These NCERT textbook solutions can be a core help for self-study and acts as a perfect self-help guidance for students.

Concepts covered in Class 12 Physics chapter 15 Communication Systems are Elements of a Communication System, Bandwidth of Signals, Bandwidth of Transmission Medium, Propagation of Electromagnetic Waves, Satellite Communication, Need for Modulation and Demodulation, Amplitude Modulation, Modulation and Its Necessity, Sinusoidal Waves, Basic Terminology Used in Electronic Communication Systems, Production of Amplitude Modulated Wave, Detection of Amplitude Modulated Wave.

Using NCERT solutions for Class 12 Physics by students are an easy way to prepare for the exams, as they involve solutions arranged chapter-wise also page wise. The questions involved in NCERT Solutions are important questions that can be asked in the final exam. Maximum students of CBSE Class 12 prefer NCERT Textbook Solutions to score more in exam.

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