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:
Answer & explanation
Answer: (c) 1, 3 and 4 only
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). ·