Q1. 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. 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?
Explanation
Statement 1 is correct: There are two types of body waves-P and S waves. The P-waves and S-waves are also known as primary waves and secondary waves, respectively. The P-waves move faster and are the first to arrive at the surface. Therefore, in a seismograph, P waves are recorded earlier than S waves. The S-waves arrive at the surface with some time lag.
Statement 2 is correct: In P-waves, the media particle vibrates parallel to the direction of the wave. Thus it causes the to-and-fro motion. Further, in the S-waves media particles vibrate perpendicular (up and down at right angles) to the direction of wave propagation i.e. in the right angle. P-waves S-waves Arrival Times Surface Waves Amplitude