UPSC Prelims 2023 – Question 65

Q 65. 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 

Correct Answer: Option (c) 

• P-waves move faster and are the first to arrive at the surface. These are also called ‘primary waves. The P waves are similar to sound waves. They travel through gaseous, liquid and solid materials. S-waves arrive at the surface with some time lag. These are called secondary waves. Hence, statement 1 is correct. 
• The P-waves are longitudinal waves, so P-wave particles vibrate parallel to the direction of the wave. But S-waves are transverse waves, so S-wave particles vibrate perpendicular to the wave direction in the vertical plane. Hence, statement 2 is correct, 

For UPSC Prelims Resources, Click here

For Daily Updates and Study Material:

Join our Telegram Channel – Edukemy for IAS

• 1. Learn through Videos – here
• 2. Be Exam Ready by Practicing Daily MCQs – here
• 3. Daily Newsletter – Get all your Current Affairs Covered – here
• 4. Mains Answer Writing Practice – here

Visit our YouTube Channel – here