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Q65·GS Paper 1 · Prelims 2023

Seismic waves — P waves recorded before S waves; P wave vs S wave particle vibration

GeographyGeomorphology & Earth ScienceStatement-basedEasyStatic

Question

Consider the following statements: Which of the statements given above is/are correct?

  1. 1.

    In a seismograph, P waves are recorded earlier than S waves.

  2. 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.

Options

a

1 only

b

2 only

c

Both 1 and 2

Answer
d

Neither 1 nor 2

Explanation

Both statements are correct. Primary (P) waves are compressional waves that travel the fastest, thus arriving earlier on the seismograph. P waves are longitudinal, vibrating particles parallel (to and fro) to propagation. Secondary (S) waves are shear waves, vibrating particles perpendicular (right angles) to propagation.

P-waves = Primary, Parallel, Push-pull. S-waves = Secondary, Shear, Side-to-side.

Answer: (c).

Question details

Year

2023

Paper

GS Paper 1

Question

Q65

Subject

Geography

Sub-topic

Geomorphology & Earth Science

Type

Statement-based

Difficulty

Easy

Nature

Static

Source hint

NCERT Geography Cl.11 Ch.3

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