Q1. State with reasons whether the following statements are True or False.
- i)) Rise time of a pulse is the time required for the amplitude to reach from 0% to 100% of the peak amplitude value. (80 words)
- ii)) Standing wave ratio of a matched transmission line is zero. (80 words)
- iii)) Amplitude modulation index for de modulating signal is 100%. (80 words)
- iv)) Multipoint communication system in telephony is more efficient than point-to-point communication. (80 words)
- v)) Though audio frequency range is 20 Hz to 20 kHz, the telephone uses only 4 kHz bandwidth per channel, still the communication is audible. (80 words)
- vi)) In superheterodyne receiver the local oscillator always operates at a fixed frequency. (80 words)
- vii)) Bandwidth of video amplifier of the monochrome receiver is narrower than that in the case of colour video amplifier. (80 words)
- viii)) Polarization discrimination technique doubles the bandwidth of the channel. (80 words)
- ix)) Token ring protocol suffers with the data collision problem. (80 words)
- x)) The compact structure of OSI model makes data transfer efficient as compared to TCP/IP model. (80 words)
Key Points:
- Rise time is 10%-90% peak amplitude, not 0%-100%, due to practical limits.
- Matched transmission lines have a Standing Wave Ratio (SWR) of 1, indicating no reflections.
- Superheterodyne local oscillator is variable, not fixed, for receiver frequency tuning.
- Telephony's 4 kHz bandwidth suffices for audible speech, despite wider audio range.
Answer: As an expert IGNOU tutor, I will now analyze each statement from the PHE-16 Communication Physics course material to determine its truthfulness and provide a comprehensive justification based on core communication principles. Each explanation adheres to the specified word limits and uses terminology consistent with the course content.