Progressive waves

Progressive waves(Mechanical)

Introduction : We are well aware of wave and types of wave i.e electromagnetic and mechanical wave. This mechanical wave are the wave which require material medium for it's propagation. In this topic we are going to see different types of progressive waves and their properties. 

Definition :Wave which travel continuously in a same direction in a given medium without change of form is called as progressive wave. There are two types of progressive  wave viz.

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A) Transverse wave : wave in which the direction of vibration of particles of the medium is perpendicular to the direction of propagation of the wave is called as transverse wave. Eg: ripples on water surface.

Transverse wave

Properties of Transverse wave :

1) All particles of the medium  vibrate in a direction perpendicular to the direction of propagation of the wave with same period and amplitude.

 2) When transverse wave passes through a medium, the medium is divided into alternate crests and troughs . 

 3) Crests and troughs advance in the medium and are responsible for transfer of energy. 

4) Transverse waves can travel through solids and on surfaces of liquids only. They can not travel through liquids and gases.  

5) When transverse waves advance through a medium there is no change in the pressure and density at any point of medium, however shape changes periodically.

 6) If vibrations of all the particles along the path of a wave are constrained to be in a single plane, then the wave is called polarised wave. Transverse wave can be polarised. 

7) Medium conveying a transverse wave must possess elasticity of shape.

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B) Longitudinal wave: wave in which the direction of vibration of particles of the medium is parallel to the direction of propagation of the wave is called as longitudinal wave.

Longitudinal wave

Properties of Longitudinal wave :

1) All the particles of medium  vibrate in a direction parallel to the direction of propagation of wave with same period and amplitude. 

2) When longitudinal wave passes through a medium, the medium is divided into regions of alternate compressions and rarefactions. 

 3) A compression and adjacent rarefaction form one cycle of longitudinal wave. The distance measured along the wave between any two consecutive points having the same phase is the wavelength of wave.

 4) For propagation of longitudinal waves, the medium should possess the property of elasticity of volume. Thus longitudinal waves can travel through solids. liquids and gases. Longitudinal wave can not travel through vacuum or free space. 

5) The compression and rarefaction advance in the medium and are responsible for transfer of energy. 

6) When longitudinal wave advances through a medium there are periodic variations in pressure and density along the path of wave and also with time. 

7) Longitudinal waves can not be polarised, as the direction of vibration of particles and direction of propagation of wave are same or parallel. 

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