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?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: C
The correct answer is (c). Both statements 1 and 2 are correct.
P waves are primary waves, which means that they travel the fastest and are the first to be recorded by a seismograph. S waves are secondary waves, which means that they travel slower than P waves and are recorded after P waves.
P waves are compressional waves, which means that the individual particles vibrate to and fro in the direction of wave propagation. S waves are shear waves, which means that the particles vibrate up and down at right angles to the direction of wave propagation.
