Consider the following activities:Identification of narcotics on passengers at airports or in aircra

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Question

Consider the following activities:Identification of narcotics on passengers at airports or in aircraftMonitoring of precipitationTracking the migration of animalsIn how many of the above activities can radars be used?

Accepted Answer

Correct Answer: B — Only twoStep-by-step Solution:RADAR (Radio Detection And Ranging) uses radio waves to detect and locate objects. Different types of radar exist — each suited to specific applications.Activity 1 — Identification of narcotics on passengers at airports: Radars cannot effectively do this. Airport security for detecting drugs/narcotics relies on: X-ray machines (baggage scanners); Ion mobility spectrometry (IMS) — 'sniffers'; CT scanners (3D imaging); Drug detection dogs. While millimetre-wave body scanners (a type of radar) are used for weapons/contraband detection on persons, they detect metal/density anomalies — NOT specifically narcotics (which are chemically indistinguishable from other organic compounds by radar). Conventional radar using radio waves cannot identify chemical substances. ✗Activity 2 — Monitoring of precipitation: Radars are extensively used for this. Weather radar (Doppler radar) detects precipitation (rain, snow, hail) by bouncing radio waves off water droplets and ice particles. The returned signal's strength indicates rainfall intensity; the Doppler shift indicates movement (wind speed, storm tracking). India's IMD (India Meteorological Department) has an extensive Doppler Weather Radar (DWR) network. ✓Activity 3 — Tracking migration of animals: Radars can be used for this. Ornithologists use weather radars (particularly Doppler radars) to study bird and bat migration — large flocks of migrating birds produce distinct radar signals. Radar allows tracking of migration altitude, speed, direction, and flight patterns over large areas at night and in poor visibility. Insects (locusts, monarch butterflies) also generate detectable radar echoes when in large numbers. ✓Only activities 2 and 3 can use radar — not activity 1.Why other options are incorrect:Option A (Only one): Incorrect. Two activities (precipitation monitoring and animal migration tracking) can use radar.Option C (All three): Incorrect. Radar cannot identify narcotics on passengers.Option D (None): Incorrect. Weather radar and biological radar are well-established technologies.Key Concept: Types of radar and applications: Weather radar (Doppler): Monitors precipitation, storm tracking, wind profiling; IMD's DWR network covers major Indian cities; Used for cyclone tracking and flood forecasting. Air traffic control (ATC) radar: Primary surveillance radar (PSR) — detects aircraft position; Secondary surveillance radar (SSR) — identifies aircraft via transponder. Military radar: Early warning; Fire control; Target tracking; Ground penetrating radar (GPR). Biological radar applications: Bird migration monitoring (aeroecology); Bat echolocation studies; Insect tracking (locusts — economically critical); Scientific research on nocturnal migration patterns. X-ray vs Radar for security: X-rays penetrate objects and create 2D/3D density images — suitable for detecting hidden objects including narcotics; Millimetre-wave scanners (mmW) — detect surface and shallow sub-surface anomalies on human body — weapons, not chemical composition; Chemical analysis (MS, IMS, NMR) — for actual substance identification. India's weather radar: IMD operates ~40+ Doppler Weather Radars; Plans to expand network for better monsoon forecasting; S-band, C-band, and X-band DWRs deployed at strategic locations.

Consider the following activities:Identification of narcotics on passengers at airports or in aircraftMonitoring of precipitationTracking the migration of animalsIn how many of the above activities can radars be used?

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Consider the following activities:Identification of narcotics on passengers at airports or in aircraftMonitoring of precipitationTracking the migration of animalsIn how many of the above activities can radars be used?

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