Duduli

Answer:- The repetition of the words of a speaker, caused by the reflection of sound from a distant object, is called an echo.

Answer:- Periodic variations of amplitude resulting from the superposition of two waves of slightly different frequencies is known as beats.

Answer:- Wave is a disturbance which transfers energy or momentum from one location to another without transfer of mass.Such a mode of transfer of energy is called wave motion.

Answer:- It is suggested that the cosmic bodies such as galaxies, stars produce gravitational waves and interact with each other through these waves.The gravitational waves are believed to propagate with the velocity of light.

Answer:- Velocity with which a wave propagates in a medium is called wave velocity.Wave velocity is also known as phase velocity because velocity of phase is same as that of velocity of wave.

Answer:- It is possible only in material media (solids, liquids and gases) which possese inertia as well as elasticity.e.g water waves & Sound waves.

Answer:- The phase is that physical quantity which determines the instantaneous displacement and direction of motion of a vibrating particle.