UPSC Prelims 2024 Q34: Science & Technology – Defence Technology
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?
- (a) Only one
- (b) Only two
- (c) All three
- (d) None
Answer: (b) Only two
Explanation
What can radar do?
Radar sends out radio or microwave pulses and reads their echoes to find the distance, speed and size of objects.
| Activity | Radar used? | Reason |
|---|---|---|
| 1. Detecting narcotics on passengers | No | Drugs are found with X-ray scanners, millimetre-wave body scanners, sniffer dogs and trace detectors, not radar |
| 2. Monitoring precipitation | Yes | Doppler weather radar maps rain, hail and storms (IMD uses a Doppler radar network) |
| 3. Tracking animal migration | Yes | Radar tracks bird and insect migration (radar ornithology) |
Common radar uses:
| Field | Example |
|---|---|
| Weather | Doppler weather radar for cyclones and rainfall |
| Aviation | Air traffic control |
| Ecology | Bird migration studies |
| Defence | Missile and aircraft detection |
Answer: (b) Only two.
Why each option is right or wrong
- (a) Incorrect. Radar is used for both precipitation and animal migration.
- (b) CORRECT. Radar tracks rain and migrating animals, but narcotics are found with X-ray scanners and trace detectors.
- (c) Incorrect. Radar does not detect narcotics hidden on passengers.
- (d) Incorrect. Doppler weather radar and radar ornithology are well-established uses.
Key point
Radar = radio echoes: used for weather (Doppler) and migration tracking; not for detecting drugs on passengers.
Remember
Radar can map rain and track migrating birds, but cannot sniff out narcotics.
Common mistakes
- Confusing airport X-ray and millimetre-wave scanners with radar.
- Forgetting that IMD uses Doppler weather radars for cyclone and rain warnings.
- Not knowing radar ornithology; flocks of migrating birds show clearly on radar screens.
Exam tip
Radar finds objects by echo, not chemicals. Any question on detecting a substance points away from radar.
Sources
- India Meteorological Department — Doppler Weather Radar network
- NCERT Class XII — Physics, Ch 8 (Electromagnetic Waves — Microwaves)