Civil Services Prep

Prelims 2020 · Science and Technology · Question 19

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:

  1. 1, 2 and 3 only
  2. 1, 2 and 4 only
  3. 1, 3 and 4 only
  4. 2, 3 and 4 only

Answer

1, 3 and 4 only

1. Correct. Visible light lies roughly in the 380–750 nm band; many technical descriptions of VLC use about 375/380 to 780 nm, so the statement is acceptable.

2. Incorrect. VLC is generally a short-range optical wireless communication technology and usually needs line-of-sight or close indoor coverage; calling it long-range is wrong.

3. Correct. VLC/Li-Fi can support much higher data rates than Bluetooth, so this statement is correct.

4. Correct. VLC uses light, not radio waves, so it does not cause electromagnetic interference (EMI) in the usual RF sense.

Hence, 1, 3 and 4 only are correct.

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