Prelims 2011 · archive
EasyWhat is the difference between Bluetooth and Wi-Fi devices?
Answer & explanation
Answer: (a) Bluetooth uses 2.4 GHz radio frequency band, whereas Wi-Fi can use 2.4 GHz or 5 GHz frequency band
Bluetooth works only in the 2.4 GHz ISM band. Wi-Fi (IEEE 802.11) standards use either the 2.4 GHz band or the 5 GHz band. So (a) is the only correct difference. (b) gets the network types of both technologies wrong, and (c) wrongly says Bluetooth needs line of sight.
- ✓ (a) Bluetooth operates in the unlicensed 2.4 to 2.4835 GHz ISM band. Wi-Fi standards such as 802.11b/g use 2.4 GHz, while 802.11a uses 5 GHz.
- ✗ (b) Bluetooth is used mainly for wireless personal area networks (WPANs), which are very short range. Wi-Fi (802.11) is the standard for wireless local area networks (WLANs). Neither is a WWAN technology.
- ✗ (c) Both are radio-frequency technologies, so neither needs a clear line of sight. Line of sight is a feature of infrared links, not Bluetooth.
- ✗ (d) Statement (b) is wrong, so (a) and (b) cannot both be correct.
Remember · Bluetooth = short-range radio, WPAN, 2.4 GHz only. Wi-Fi (802.11) = WLAN, 2.4 GHz and 5 GHz. Neither needs line of sight, unlike infrared.
Sources
- NIST – Bluetooth Security: Protecting Wireless Networks and Devices (based on SP 800-121) ↗ “Bluetooth operates in the unlicensed 2.4 gigahertz (GHz) to 2.4835 GHz Industrial, Scientific, and Medical (ISM) frequency band.”
- NIST SP 800-121 Rev. 1, Guide to Bluetooth Security ↗ “Bluetooth is an open standard for short-range radio frequency (RF) communication. Bluetooth technology is used primarily to establish wireless personal area networks (WPANs).”
- NIST SP 800-97, Establishing Wireless Robust Security Networks: A Guide to IEEE 802.11i ↗ “802.11a 54 Mbps 50-100 meters 5 GHz Not compatible with 802.11b 802.11b 11 Mbps 50-100 meters 2.4 GHz”
Question: UPSC Civil Services (Preliminary) 2011, General Studies paper. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). ·