UPSC Prelims 2016 · Question 30 of 98

UPSC Prelims 2016 question on Lifi Technology

With reference to ‘LiFi’, recently in the news, which of the following statements is/are correct?

1. It uses light as the medium for high-speed data transmission.

2. It is a wireless technology and is several times faster than ‘WiFi’.

Select the correct answer using the code given below.

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: C. Both 1 and 2

Verdict

The answer is both 1 and 2. LiFi uses light for high speed data transmission and is a wireless technology several times faster than WiFi.

Analysis

Statement 1 is CORRECT. LiFi modulates visible light from LED sources to carry data, and light is already used for data transmission in fibre optic cables and point to point links. Statement 2 is CORRECT. LiFi is wireless and offers far higher data rates than conventional WiFi, because the visible light spectrum is vastly wider than the radio bands available to WiFi. It also enables connectivity in environments where radio is restricted, such as aircraft cabins, hospitals and hazardous locations.

Source

The Hindu report on data transmission through light.

How to crack it

Reason from the physics rather than the product. Data rate scales with available bandwidth, and the visible light spectrum is orders of magnitude wider than the radio spectrum allotted to WiFi, so a light based system being faster is a prediction rather than a fact to recall. The trade off follows too: light does not pass through walls, which is a security advantage and a coverage limitation. Deriving both the strength and the weakness from one property is what makes this reusable.

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