UPSC Prelims 2016 · GS Paper I
Question 5: Science and 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.
AnswerUPSC’s answer is (c).
Li-Fi (Light Fidelity) sends data through very fast flickering of LED light, too fast for the eye to notice, so light is the transmission medium. It is a wireless technology, and tests have claimed speeds many times faster than WiFi, which uses radio waves. It needs line of sight and cannot pass through walls, which is its main limitation.
- 1. Li-Fi uses visible light from LEDs to carry data.
- 2. It is wireless and claimed to be several times faster than WiFi.
How you could have got this
- If you were sure statement 1 is correct, (b) and (d) go: each of them leaves 1 out.
What you needed to know: Li-Fi uses visible light from LEDs to carry data.
- Then, if you were sure statement 2 is correct, (a) goes: it leaves 2 out.
What you needed to know: It is wireless and claimed to be several times faster than WiFi.
Only (c) is left. This one needs every statement.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Statement 2 is also correct: Li-Fi is wireless and claimed to be much faster.
- (b) Statement 1 is also correct: light is the medium.
- (c) Right: both statements are correct.
- (d) Both statements are correct, so 'neither' fails.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2016, General Studies Paper I, Series A. The paper on upsc.gov.in.