Question

Assertion: Longitudinal waves are called pressure waves.
Reason: Propagation of longitudinal waves through a medium involves changes in pressure in the medium.

• A. Both assertion and reason are correct and reason is the correct explanation of assertion.
• B. Both assertion and reason are correct but reason is not a correct explanation of assertion.
• C. Assertion is correct but reason is incorrect.
• D. Assertion is incorrect but reason is correct.

Answer 1

The correct option is A Both assertion and reason are correct and reason is the correct explanation of assertion.

When longitudinal waves propagates through a medium, it causes displacement of particles along the direction of wave propagation.

Hence at some points particles are close to each other while at some points they are farther apart. This creates a density difference in medium, due to which pressure difference arises in the material medium.
Since propagation of longitudinal waves through a medium creates pressure disturbances in the medium, hence these waves are called pressure waves.