UPSC Prelims 2016 Q5: Science & Technology – Computer & Information 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.
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (c) Both 1 and 2
Explanation
LiFi (Light Fidelity)
LiFi sends data through visible light from LED bulbs that flicker faster than the eye can see.
The term was coined by Harald Haas in 2011.
| Statement | Verdict | Fact |
|---|---|---|
| 1. It uses light as the medium for high-speed data transmission | Correct | It is a form of Visible Light Communication |
| 2. It is a wireless technology and is several times faster than WiFi | Correct | Lab tests have shown speeds many times higher than WiFi |
LiFi and WiFi compared:
| Feature | LiFi | WiFi |
|---|---|---|
| Medium | Light (LED) | Radio waves |
| Speed | Much higher | Lower |
| Passes through walls | No | Yes |
| Security | Higher (stays in the room) | Lower |
| Useful in | Aircraft, hospitals (no radio interference) | General use |
Answer: (c) Both 1 and 2.
Why each option is right or wrong
- (a) Incorrect. Statement 2 is also true: LiFi is wireless and much faster than WiFi.
- (b) Incorrect. Statement 1 is also true: LiFi uses light to transmit data.
- (c) CORRECT. LiFi uses light for data and is a wireless technology faster than WiFi.
- (d) Incorrect. Both statements correctly describe LiFi.
Key point
LiFi: wireless data through visible light from LEDs (Harald Haas, 2011); faster than WiFi but cannot pass through walls.
Remember
LiFi = data through LED light, faster than WiFi.
Common mistakes
- Thinking LiFi needs optical fibre; it is wireless, through open air.
- Assuming LiFi works through walls like WiFi.
- Confusing LiFi with laser communication between satellites.
Exam tip
Li = light, Wi = wireless radio. Light is faster but is blocked by walls.
Sources
- Harald Haas — 'Wireless data from every light bulb' (TED Global, 2011)
- IEEE 802.15.7 — Standard for Short-Range Optical Wireless Communications