🧷 Authentic Classroom Explanation by IAS Monk

📌 The Question:

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 radars be used?

(a) Only one
(b) Only two
(c) All three
(d) None

✅ Answer: (b) Only two

🧑‍🏫 Classroom Explanation:

Radar (Radio Detection and Ranging) works by transmitting radio waves and analysing the reflected signals (echoes) to detect, locate, and track objects.

🔹 Activity 1 – Identification of narcotics at airports ❌

• Narcotics detection primarily uses X-ray scanners, CT scanners, sniffer dogs, and chemical sensors.
• Radar waves are not suitable for identifying chemical substances like drugs.
  ➡️ Hence, not correct.

🔹 Activity 2 – Monitoring of precipitation ✅

• Weather radars (Doppler radars) are widely used to monitor:
  • Rainfall intensity
  • Storm systems
  • Cyclones and cloud movement
    ➡️ Correct.

🔹 Activity 3 – Tracking migration of animals ✅

• Radar is extensively used in ecological and biological studies to track:
  • Bird migration
  • Bat movement
  • Insect swarms
• Radars help determine altitude, speed, direction, and timing of migration.
  ➡️ Correct.

✔️ Therefore, two activities (2 and 3) use radar.

🔍 Curiosity Raiser:

🦅 Ever wondered how scientists track birds flying thousands of kilometres at night — without GPS tags?
👉 Radar sees what eyes cannot.

📚 Enrichment Notes (UPSC Edge):

• Doppler Weather Radar (DWR) is used by IMD for cyclone tracking
• Radar ornithology is a growing scientific field
• Radar cannot identify chemical composition, only objects and motion
• Millimetre-wave scanners used in airports are not classical radars

🧘 IAS Monk Whisper:

📡 Some tools do not search for substances — they search for movement.
Understanding the tool reveals its limits.