UPSC CSE Prelims
Electronics and Communication Systems Previous Year Questions (PYQs)
Practice solved questions for Electronics and Communication Systems with detailed step-by-step solutions, key insights, and trend analysis for UPSC CSE PRELIMS.
Solved Previous Year Questions
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Consider the following communication technologies:
- Closed-circuit Television
- Radio Frequency Identification
- Wireless Local Area Network
Which of the above are considered Short-Range devices/technologies?
Detailed Explanation:
Answer: Option 4 — 1, 2 and 3
All three technologies—CCTV, RFID, and WLAN—are classified as short-range communication devices. Short-range technologies typically operate within a few centimeters to a few hundred meters, unlike long-range technologies such as cellular networks or satellite communication.
✅ Closed-Circuit Television (CCTV) – Short-Range: CCTV systems use cables or wireless connections with limited range, typically confined to a building or specific premises, operating within tens to hundreds of meters.
✅ Radio Frequency Identification (RFID) – Short-Range: RFID uses radio waves for identification and tracking, with typical reading ranges from a few centimeters to about 10 meters depending on the tag type (passive, active, or semi-passive).
✅ Wireless Local Area Network (WLAN/Wi-Fi) – Short-Range: WLAN networks typically operate within 20-100 meters indoors and up to 300 meters outdoors, making them short-range compared to wide-area networks like cellular or satellite systems.
📝 Short Notes: Short-Range Communication Technologies
| Technology | Typical Range | Primary Application | Frequency Band |
|---|---|---|---|
| CCTV (Wireless) | 50-300 meters | Video surveillance | 2.4 GHz, 5 GHz |
| RFID (Passive) | Few cm to 10 meters | Asset tracking, access control | 125 kHz, 13.56 MHz, 860-960 MHz |
| RFID (Active) | Up to 100 meters | Long-range tracking | 433 MHz, 2.45 GHz |
| WLAN/Wi-Fi | 20-100 m (indoor), up to 300 m (outdoor) | Internet connectivity, data transfer | 2.4 GHz, 5 GHz, 6 GHz |
| Bluetooth | 1-100 meters | Personal area networking | 2.4 GHz |
| NFC | Up to 10 cm | Contactless payments, pairing | 13.56 MHz |
- Short-range vs Long-range: Short-range technologies operate within localized areas (centimeters to hundreds of meters), while long-range technologies like cellular networks (kilometers) and satellite communication (global coverage) serve wider geographical areas.
- Power consumption: Short-range devices typically consume less power, making them suitable for battery-operated applications.
- Data rate: Generally, shorter ranges allow for higher data transfer rates (e.g., Wi-Fi offers Mbps to Gbps speeds).
- Applications: Short-range technologies are ideal for home automation, personal devices, local networking, surveillance, and proximity-based services.
The terms ‘Event Horizon’, ‘Singularity’, `String Theory’ and ‘Standard Model’ are sometimes seen in the news in the context of
Detailed Explanation:
Answer: Option 1 — Observation and understanding of the Universe
All four terms are fundamental concepts in cosmology and theoretical physics. Event Horizon is the boundary around a black hole beyond which nothing can escape its gravitational pull. Singularity refers to a point of infinite density and gravity, such as at the center of a black hole or the initial state of the Big Bang. String Theory is a theoretical framework attempting to unify all fundamental forces of nature by describing particles as vibrating strings. Standard Model is the established theory in particle physics describing fundamental particles and three of the four forces (excluding gravity). These concepts are central to understanding the structure, origin, and evolution of the Universe, making Option 1 the correct answer.
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