2011 GS Paper I, all questions
UPSC Prelims 2011 · GS Paper I
Question 57: Science and Technology
What is the difference between Bluetooth and Wi-Fi devices ?
aBluetooth uses 2·4 GHz radio frequency band, whereas Wi-Fi can use 2·4 GHz or 5 GHz frequency band
bBluetooth is used for Wireless Local Area Networks (WLAN) only, whereas Wi-Fi is used for Wireless Wide Area Networks (WWAN) only
cWhen information is transmitted between two devices using Bluetooth technology, the devices have to be in the line of sight of each other, but when Wi-Fi technology is used the devices need not be in the line of sight of each other
dThe statements (a) and (b) given above are correct in this context
AnswerThe answer is (a).
Bluetooth is a short-range technology for personal area networks and works in the 2.4 GHz radio band. Wi-Fi is used for wireless local area networks and can work in the 2.4 GHz or the 5 GHz band. Neither needs line of sight, since both use radio waves that pass through walls, unlike infrared. Bluetooth is not for WLAN only, and Wi-Fi is not a wide area technology, so option (b) is wrong.
Why each option is right or wrong
- (a) Right: Bluetooth uses 2.4 GHz; Wi-Fi can use 2.4 GHz or 5 GHz.
- (b) Wi-Fi is not a wide-area technology; it is a local-area one.
- (c) Neither technology needs line of sight; that describes infrared.
- (d) Statement (b) is wrong, so this fails.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2011, General Studies Paper I, Series A. The paper on upsc.gov.in.