Q: 75 (IAS/2023)
question_subject:
Science
question_exam:
IAS
stats:
0,15,7,4,2,15,1
Option 1 is correct. In a seismograph, P waves (Primary waves) are indeed recorded earlier than S waves (Secondary waves). This is due to the fact that P waves travel faster through the earth`s crust than S waves.
Option 2 is also correct. P waves cause particles to vibrate in the direction of the wave. This means that as the wave moves forward, the particles also move forward and backward along the same line. However, in the case of S waves, the particle movement is perpendicular to the direction of wave propagation i.e., they move up and down when the wave moves forward. This is why S waves are also known as shear waves or transverse waves.
Therefore, the correct answer is option 3, Both 1 and 2 are correct.