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# Xam Idea Class 12 Physics Chapter 15 Solutions: Communication Systems

Xam Idea Class 12 Physics Solutions Chapter 15 ‘Communication Systems’ is one of the best learning guides for Class 12 board exams. It is also extremely helpful if you are preparing for some of the competitive exams like JEE and NEET. The chapter communication system includes questions that deal with a collection of systems that are used for connection, communication, transmission and interconnection. You will gain knowledge of how they are arranged into three categories depending on its uses like media, technology as well as application. With the help of our Xam Idea solutions for Communication Systems, you can learn about elements of communication systems, the bandwidth of signals and transmission medium, propagation of electromagnetic waves and modulation and its requirements.

Xam Idea Class 12 Physics Solutions for Communication Systems consists of questions that are divided into four different sections. The four categories of questions are very short answer type questions, short answer question type –I, short answer question type –II, long answer type questions. The questions are mainly based on essential components of communication system, ground and sound wave propagation, the function of the repeater, modulator and demodulator, mode of propagation, describing modulation with diagram and how amplitude modulation is achieved. Some previous year questions about LOS communication and schematic arrangement of transmitting a message signal are also included in the exercises.

You need a solid base in Physics to successfully clear any exams no matter whether it is CBSE Class 12 exams or any competitive exams. Instasolv solutions for Xam Idea Class 12 Physics Communication Systems are prepared by our experienced subject matter experts in an easy but detailed manner. Both the theoretical and numerical questions solutions are provided by us keeping in mind the level of understanding of Class 12 students.

## Important Topics for Xam Idea Class 12 Physics Solutions Chapter 15: Communication system.

The three basic elements of the communication system are the transmitter, channel and the receiver. In this system, the transmitter and the receiver are situated in a different place and the channel is responsible for making a connection between the transmitter and the receiver.

Information source: The source creates a signal of information that needs communication.

Signal: Information in electrical form for transmission is called a signal.

Transmitter: One that is responsible for converting the source signal form for transmission through the channel.

Channel: One that connects the transmitter with the receiver is called a channel. The channel can be any form like wires, wireless.

Noise: When a transmitted signal circulates in the channel, it might get warped because of channel imperfection. Noise refers to some of the unwanted signals that can disturb the whole process of communication from the transmitter to the receiver.

Receiver: Because of noise and other factors, the corrupted version of the signal comes to the receiver. The receiver is responsible for reconstructing the signal into some recognisable form of the original message for delivering it to the user. The signal by the receiver creates the output.

Elements of Communication:

There are two basic modes of communication that are

• Point to point mode of communication where the communication takes place through a link in between a single transmitter and a receiver. Telephony is a good example of this mode of communication.
• Broadcast mode of communication is something where there are large numbers of receivers in correspondence to a single transmitter. Good examples are radio and television.
• Digital mode of transmission: It is an orderly sequence of symbols chosen from a finite set of discrete elements.

The bandwidth of transmission medium: Some of the common forms of transmission media is free space, fibre optic cable, wire.

Propagation of electromagnetic waves: For long-distance transmission, signals are directed into space utilizing devices known as antennas. The radiated signals circulate as electromagnetic waves and the propagation mode is affected by the earth and its atmosphere. Near the earth surface, the electromagnetic waves circulate in the form of surface waves. It is useful till a few MHZ frequencies. Long-distance communication between two points on the earth is gained through the reflection of electromagnetic waves. Such waves are used for line of sight communication and satellite communication.

Modulation: The procedure of altering some characteristics such as amplitude, frequency or phase of a carrier wave according to the signal intensity is called modulation. Different types of modulation are amplitude modulation, frequency modulation and phase modulation.

The amplitude of modulation is the amplitude of the carrier wave alterations based on the intensity of the signal. The variation in amplitude of the carrier wave is at the signal frequency. It is produced by application of the signal message and the carrier wave to some non-linear device followed by a bypass filter.

Modulation factor: It is the ratio of change of amplitude of carrier wave to the altitude of a normal carrier wave.

Demodulation: It is the process of recovering the signal intelligence from any modulated carrier wave.

### Exercise Discussion of Xam Idea Class 12 Physics Solutions Chapter 15: Communication systems

Xam Idea Class 12 Physics Solutions Chapter 15 include 89 questions in total covering all important aspects of the chapter communication system. The whole exercise is divided into four categories.

• There are about 41 questions under this section. It is further divided into two sections PYQ (past years questions) and OIQ (objective inventory questionnaires).
• Under the PYQ section, there are 16 questions where you have to answer some one-line answers to some of the important questions of the chapter.
• The questions are mainly based on an essential component of the communication system, the difference between transductor and repeater, skywave propagation, modulation, sidebands, mode of communication for telephonic communication.
• Under the OIQ section, there are 25 questions where you have to identify parts of a generalised communication system, types of modulation in analogue communication, frequency of the modulated carrier.

• There are a total of 19 questions under this section. It is divided into two important categories PYQ and OIQ.
• Under PIQ section there are 14 questions that ask about functions of modulator and demodulator, repeater, mode of communication in satellite communication, range of transmission if TV transmission, the difference between point to point and broadcast communication modes.
• Under the OIQ section, there are 5 questions where you need to answer about frequency ranges, sky waves suitable for TV signal transmission.

• There are a total of 26 questions under this category. It is further divided into PYQ and OIQ.
• Under the PYQ category, about 17 questions are asking about describing the function of components of a communication system by drawing block diagrams and defining modulation with block diagrams.
• It also includes how to achieve amplified modulation, along with some numerical questions.
• Under OIQ sections there are 9 questions based on the optical transmission system, TV transmission system, modulation index.

• These categories consist of 3 questions that need descriptive long answers.
• You are required to answer about describing the term LOS communication and the types of waves used for this communication, and the drawback of a communication system arrangement with block diagrams.
• Some questions are based on deriving an expression for covering a range of TV transmission towers.
• All those questions covered in each category will certainly assist you in appearing exams with much confidence.

## Why Use Xam Idea Class 12 Physics Solutions Chapter 15: Communication systems by Instasolv

• Instasolv solutions for Xam Idea Class 12 Physics are highly informative and well structured for you.
• These solutions will assist you in answering questions in not only CBSE exams but also for competitive exams like JEE and NEET with much confidence.
• The solutions provided by our expert team will fuel your problem-solving skills and offer you the ability to think out of your box.
• No matter how hard the question is in the exam you can answer it to the maximum extent.
• The Xam Idea Class 12 Physics solutions besides solving your NCERT book problems help in making your Communication systems concepts clear.