Consider the following statements:
I. In a seismograph, P waves are recorded earlier than S waves.
II. 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.I only
B.II only
C.Both I and II✓ Correct
D.Neither I nor II
Explanation
Both statements are correct. P waves (Primary waves) are longitudinal/compressional waves that travel faster than S waves (Secondary waves), so they are always recorded first on a seismograph. In P waves, particles vibrate parallel to the direction of wave propagation (to and fro), while in S waves, which are transverse waves, particles vibrate perpendicular (up and down) to the direction of wave propagation.
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