Consider the following activities:
- 1.Identification of narcotics on passengers at airports or in aircraft
- 2.Monitoring of precipitation
- 3.Tracking the migration of animals
In how many of the above activities can the radars be used?
Answer & explanation
Answer: (b) Only two
Radar sends out radio pulses and times their echoes to find the distance and speed of whatever reflects them. That makes it excellent for watching rain, hail and snow and for following flocks of migrating birds or swarms of insects in the sky, but an echo cannot reveal what chemical a passenger is carrying, so radar is not a narcotics detector.
- ✗ 1. Drugs on passengers are found with X-ray and body scanners, trace-detection equipment and sniffer dogs; radar only tells where an object is and how it moves, not what substance it is.
- ✓ 2. Doppler weather radars measure reflected pulses from raindrops and ice; dual-polarisation radars can tell rain, hail, snow and ice pellets apart.
- ✓ 3. Weather-radar networks also pick up birds, bats and insects aloft; ornithologists use these echoes to map and forecast nightly bird migration.
Remember · Radar (RAdio Detection And Ranging) gives range and velocity of targets: rain, storms, aircraft, ships, bird and insect movements. It cannot identify substances such as drugs.
Sources
- NOAA JetStream: How radar works ↗ “As the name implies, radars use radio waves to determine the distance and velocity of the targets they hit. … Dual-pol radar helps NWS forecasters clearly identify rain, hail, snow, the rain/snow line, and ice pellets, improving forecasts for all types of weather.”
- U.S. Geological Survey, Realizing the biological potential of weather radar ↗ “Although designed for meteorological applications, these radars readily detect the movements of hundreds of species of birds, bats, and insects.”
Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·