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 ✓ UPSC's answer
- (d) 2, 3 and 4 only
Why the answer is (c)
• Visible Light Communication (Li-Fi) transmits data by rapidly modulating LED light in the visible band of roughly 375–780 nm (statement 1).
• Because light does not penetrate walls, VLC is a short-range optical wireless technology, so statement 2 is wrong.
• Statement 3 is correct: VLC can reach gigabit speeds, far beyond Bluetooth's few Mbps.
• Statement 4 is correct: light causes no radio-frequency electromagnetic interference, making VLC usable in hospitals and aircraft.
• Hence 1, 3 and 4 only, option (c).
Why the other options are wrong
- (a) 1, 2 and 3 only
- Statement 2 is wrong: VLC is short-range.
- (b) 1, 2 and 4 only
- Statement 2 is wrong; statement 3 is correct.
- (d) 2, 3 and 4 only
- Statement 2 is wrong; statement 1 is correct.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2020, held on 4 October 2020. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.