📝 Unguided media: Infrared

📖 From Data Communication & Networks • 7. Transmission Media • 13 questions available

Practice MCQs for Unguided media: Infrared. Test your knowledge with carefully crafted questions across easy, medium, and hard difficulty levels.

🔄 Last updated: 2026-07-31

Easy Questions

Medium Questions

Hard Questions

📝 Sample Questions

Q1. What is the typical wavelength range used for infrared data communication?

🔹 A. 700 nm – 900 nm

🔹 B. 900 nm – 1.2 µm

🔹 C. 850 nm – 950 nm

🔹 D. 1.2 µm – 2.5 µm

💡 Difficulty: easy | ✅ Correct: C

Q2. An IR link uses pulse‑width modulation (PWM) to encode data. If the duty cycle is reduced while keeping the carrier frequency constant, what is the most likely impact on the average received power?

🔹 A. It increases linearly with duty cycle

🔹 B. It remains unchanged

🔹 C. It decreases proportionally to the duty cycle

🔹 D. It oscillates unpredictably

💡 Difficulty: medium | ✅ Correct: C

Q3. Considering eye safety standards, why are infrared wavelengths between 800 nm and 1400 nm classified as Class 1 (safe) for typical consumer devices?

🔹 A. They are absorbed by the cornea, preventing retinal damage

🔹 B. They are reflected by the iris, reducing exposure

🔹 C. Their photon energy is too low to cause ionization

🔹 D. The blink reflex is faster at these wavelengths

💡 Difficulty: hard | ✅ Correct: A

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🔗 Related Topics

📝 Introduction to Transmission Media in Physical Layer 📝 Guided media: Twisted Pair Cable 📝 Guided media: Coaxial Cable 📝 Guided media: Fiber Optic Cable 📝 Unguided media: Wireless

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