UPSC Prelims 2020 · Question 19 of 100

UPSC Prelims 2020 question on Visible Light Communication

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
Show answer

Answer: C. 1, 3 and 4 only

Verdict

Correct statements: 1, 3 and 4 → Option (c).

Statement by statement

Statement 1 – CORRECT: The signals in the 380-780 nm wavelength interval of the electromagnetic spectrum are the light signals that can be detected by the human eye. VLC uses this range. Hence statement 1 is correct.

Statement 2 – INCORRECT: VLC is NOT known as long-range optical wireless communication. Light cannot penetrate obstacles such as walls, so it is a short-range technology. Hence statement 2 is not correct.

Statement 3 – CORRECT: It is possible to achieve illumination and data transfer simultaneously by means of LEDs. LED lighting can be modulated at very high frequencies, with a cycle as short as nanoseconds, allowing richer information transfer. The visible light spectrum is 10,000 larger than the radio spectrum, allowing large data transmission faster than Bluetooth. Hence statement 3 is correct.

Statement 4 – CORRECT: As a bonus, VLC doesn't cause electromagnetic interference. Hence statement 4 is correct.

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