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?

1. A. Only one
2. B. Only two
3. C. All three
4. D. None

Answer: B

Explanation

Radar technology, which uses electromagnetic waves, has diverse applications. Statement 2 is correct because weather radars (Doppler radars) are commonly used to detect and monitor precipitation, including rain, snow, and hail. Statement 3 is also correct; specialized radars are employed to track the migration patterns of birds, bats, and even insects, providing valuable ecological data. However, statement 1 is incorrect. While airports use various scanning technologies for security, such as X-ray machines and metal detectors, conventional radar is not typically used for identifying narcotics on passengers or in aircraft. Millimeter-wave scanners exist but are distinct from traditional radar for this purpose. Therefore, only two activities (2 and 3) can use radars. This question assesses the practical applications of technology, a recurring theme in UPSC Science & Technology.