दृश्य प्रकाश संचार (VLC) तकनीकी के संदर्भ में, निम्नलिखित में से कौन-से कथन सही हैं ?
- 1.VLC, 375 से 780 nm वाली विद्युत्-चुम्बकीय स्पेक्ट्रमी तरंगदैर्घ्यों का उपयोग करती है ।
- 2.VLC को दीर्घ-परासी प्रकाशी बेतार संचार के रूप में जाना जाता है ।
- 3.VLC ब्ल्यूटूथ की तुलना में डेटा की विशाल मात्रा को अधिक तेज़ी से प्रेषित कर सकता है ।
- 4.VLC में विद्युत्-चुम्बकीय व्यतिकरण नहीं होता है ।
नीचे दिए गए कूट का प्रयोग कर सही उत्तर चुनिए :
Read this question in English
With reference to Visible Light Communication (VLC) technology, which of the following statements are correct?
1. VLC uses electromagnetic spectrum wavelengths 375 to 780 nm.
2. VLC is known as long-range optical wireless communication.
3. VLC can transmit large amounts of data faster than Bluetooth.
4. VLC has no electromagnetic interference.
Select the correct answer using the code given below:
(a) 1, 2 and 3 only · (b) 1, 2 and 4 only · (c) 1, 3 and 4 only · (d) 2, 3 and 4 only
उत्तर और व्याख्या · explanation in English
Answer: (c) केवल 1, 3 और 4
VLC sends data by rapidly varying visible light, roughly 380 to 780 nm in wavelength, from LEDs. It is a high-speed, indoor, short-range technology, so statement 2 (long-range) is the wrong one; the other three statements are correct.
- ✓ 1. VLC works in the visible part of the spectrum, taken as about 380-780 nm in the ITU standard; UPSC's 375 nm lower limit is a marginal variation of the same band.
- ✗ 2. VLC is designed for high-speed indoor, in-premises use, not for long-range links. It is short-range optical wireless communication.
- ✓ 3. Light offers a far wider bandwidth than radio waves, and a peer-reviewed review lists a higher transmission rate and high bandwidth among VLC's advantages over radio-frequency links, which is why it can carry large amounts of data faster than Bluetooth.
- ✓ 4. UPSC's key counts this as correct: VLC carries data on light, not on radio waves, so it is not subject to radio-frequency electromagnetic interference (the review lists reduced interference among VLC's advantages over radio).
Remember · VLC (Li-Fi) = data on visible light (about 380-780 nm): fast, short-range, indoor, free of radio interference.
Sources
- ITU-T Recommendation G.9991 (03/2019), High-speed indoor visible light communication transceiver ↗ “Two wavelength bands are defined in this Recommendation, which are visible light (380 nm-780 nm) and infrared (800 nm-1675 nm). … transceivers for in-premises applications designed for the high-speed optical wireless transmission of data using visible light and infrared communications.”
- Recent Advances in Micro-LEDs for Visible Light Communications (review article, PubMed Central) ↗ “VLC has become more popular recently because of its many advantages over conventional radio frequencies, including a higher transmission rate, high bandwidth, low power consumption, fewer health risks, and reduced interference.”
Question and answer: UPSC's official GS Paper I (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). ·