UPSC Previous Year Question | Prelims GS | 2023

Consider the following statements: 1. In a seismograph, P waves are recorded earlier than S waves. 2. In P waves, the individual particles vibrate to and fro in the direction of wave propagation whereas in S waves, the particles vibrate up and down at right angles to the direction of wave propagation. Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2

Answer

Correct Answer

Both 1 and 2

Explanation

P (primary) waves travel faster and are recorded before S (secondary) waves on a seismograph (statement 1 true). P waves are longitudinal (particle motion parallel to propagation), and S waves are transverse (particle motion perpendicular to propagation), matching statement 2.

Topics: economy, government budget, non debt capital receipts, primary deficit