Duduli

The velocity with which slowly varying envelope of modulated wave(wave packet) due to group of waves travels through a medium is called group velocity.

Consider an example :- Emission of radiation by an electron when it jump from higher energy state to lower energy state produces a light burst.Each light burst occurs over a period of 10-⁸s only, during which period a train of finite length having a certain limited number of wave oscillations is generated.such a light burst is known as a wave train or a wave packet.

A plane progressive wave is one which travels onward through the medium in a given direction without attenuation( i.e  amplitude constant).

Answer:- It is the impedance offered by a string to transverse, progressive waves and its defined as the ratio of transverse force to the transverse velocity.

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 represents the instantaneous displacement and direction of motion of a vibrating particle.