Question

The waves responsible for elongating and squeezing of the material while propagating are

• A. S − waves
• B. L − waves
• C. R − waves
• D. P − waves

Hint:

Seismic waves travel through the Earth in different ways. The way a wave moves the material it passes through tells us its type.

Answer 1

The Correct Option is D

Step 1: Focus on the motion described.
The question asks which wave stretches and squeezes the material as it moves through it.

Step 2: Recall longitudinal motion.
In a longitudinal wave the particles vibrate back and forth along the same line as the wave travels, which creates compressions (squeezing) and rarefactions (stretching).

Step 3: Identify that wave.
Among seismic waves, the P-wave (primary wave) is longitudinal, so it elongates and squeezes the material.

Step 4: Rule out the others.
S-waves shake the material sideways, while L-waves and R-waves are surface waves with their own motions, not the simple push-pull type.

Step 5: Match the option.
The stretching and squeezing motion belongs to P-waves.

Step 6: Conclude.
The required wave is the P-wave.
\[ \boxed{\text{P} - \text{waves}} \]