2026 GS Paper I, all questions

UPSC Prelims 2026 · GS Paper I

Question 47: Science and Technology

Which of the following statements with regard to drone swarms is/are correct ?

  1. 1.They use Terahertz band of frequency to communicate with the command centre.
  2. 2.Individual drones in the swarm can communicate with other drones in the swarm.
  3. 3.GPS Spoofing is a commonly used technique to counter drone swarm attack.

Select the answer using the code given below :

a1 only
b2 and 3 only
c1 and 2 only
d1, 2 and 3

AnswerUPSC’s answer is (b).

A drone swarm is a group of drones that share information with one another (statement 2) and with the controller, using ordinary radio links such as mesh radio, Wi-Fi or cellular bands. Terahertz waves are short-range and easily absorbed by the atmosphere, so they are not the usual link to a command centre, which makes statement 1 wrong. Because swarms rely on satellite navigation, GPS spoofing and jamming are common counter-measures (statement 3).

  • 1. Terahertz bands are short-range and are not what swarms use to link to command.
  • 2. Swarm drones communicate among themselves.
  • 3. Spoofing satellite navigation signals is a common counter to swarm attacks.

How you could have got this

  1. If you were sure statement 1 is not correct, (a), (c) and (d) go: each of them includes 1.

    What you needed to know: Terahertz bands are short-range and are not what swarms use to link to command.

Only (b) is left. You didn’t need statements 2 or 3.

This follows UPSC’s provisional key; the final key could change it.

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) Wrong: swarms do not use the terahertz band to talk to the command centre.
  • (b) Right: drones talk to one another, and GPS spoofing is a counter-measure.
  • (c) Wrong: statement 1 on terahertz is false.
  • (d) Wrong: statement 1 is false.

Only the provisional key (27 May 2026) was found; the final key replaces it when found.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

Practise this paper timedPrevious questionNext question

Source: UPSC, Civil Services (Preliminary) Examination 2026, General Studies Paper I, Series A. The paper on upsc.gov.in.