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Communication Systems — Revision Notes

NIOS · Class 12 · Physics

Communication Systems revision notes for NIOS Class 12 Physics: 4 topics in quick points. Part of the NIOS Class 12 Physics syllabus.

45 questions30 flashcards4 formulas & key relations5 concepts

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A block diagram illustrating the fundamental components of a communication system: Information Source, Input Transducer, Transmitter, Communication Channel, Receiver, Output Transducer, and Destinatio
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Key Topics to Revise

1

Elements of a Communication System

  • Every communication system has three fundamental components: Transmitter, Channel (medium), and Receiver.
  • The transmitter processes and sends the signal; the channel carries it; the receiver intercepts and decodes it.
  • A transducer converts one form of energy to another (e.g., microphone converts sound to electrical signal).
2

Analog and Digital Signals

  • Analog signals vary continuously with time — they can take any value within a range (e.g., human speech, music).
  • Digital signals are discrete — they exist only as specific values (0 or 1) at distinct time intervals.
  • In digital format, signals are represented as a string of bits (binary digits), where each bit is either ON (1) or OFF (0).
3

Bandwidth of Signals and Electromagnetic Waves

  • Human speech has a bandwidth of about 4 kHz (frequency range: 300 Hz to 3400 Hz for telephone).
  • AM radio transmission bandwidth: approximately 10 kHz.
  • FM radio transmission bandwidth: approximately 15 kHz (FM gives better quality than AM).
4

Radio Frequency Bands and Their Applications

  • ELF (Extremely Low Frequency): < 3 kHz, wavelength > 100 km — used for mains electricity.
  • VLF (Very Low Frequency): 3–30 kHz, wavelength 10–100 km — used for SONAR.
  • LF (Low Frequency): 30–300 kHz, wavelength 1–10 km — marine navigation, AM Long Wave (144–351 kHz).

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Full Notes

Key Concepts

Every communication systemANALOGUE SIGNALBandwidth is the range of frequenciesElectromagnetic waves are used as carriersGuided media physically connect the transmitter

Frequently Asked Questions

What are the important topics in Communication Systems for NIOS Class 12 Physics?
Key topics in Communication Systems include Elements of a Communication System, Analog and Digital Signals, Bandwidth of Signals and Electromagnetic Waves, Radio Frequency Bands and Their Applications. Study these first, then practise questions on each for the NIOS Class 12 board exam.
How should I revise Communication Systems for the NIOS Class 12 board exam?
Learn the core ideas first, then work through the 45 practice questions on Communication Systems. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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