T1.1 Wave Motion (Longitudinal and Transverse Wave)

"Never mistake motion for action !!"

There are two types of wave in terms of mode of vibration of the particles: Longitudinal waves and Transverse waves.

Longitudinal waves:
A wave in which the particles of the medium vibrating in the direction (Parallel) of propagation. Sound wave in air and wave in spring are the example of Longitudinal waves, which are suddenly compressed (Compression) and released (Rarefaction), as shown in figure below. The distance between two nearest Compressions and Rarefaction is equal to one wavelength ($\lambda$).

Fig 1: Longitudinal waves

Transverse waves:
A wave in which the particles of the  medium vibrates at right angles (Perpendicular) to the direction of propagation. Waves on water surface, Electromagnetic waves (Light, X-Rays, Micro waves, U-V rays), Vibrating Guitar string are the example of transverse waves.


Fig 2: Transverse waves

 
During the oscillation, the particle move upward or downward from the plane passing through their mean position. The maximum distance above the mean position is called Crest. And the maximum distance below the mean position is called Trough, as shown in figure below. Thus in the transverse wave Crest and Trough are appear alternatively.

 
This is the animated video to visualize the Transverse waves and Longitudinal waves[1].


Difference between Transverse and Longitudinal waves:


Transverse Waves
Longitudinal Waves
     1.      The particles of the medium vibrate in the direction perpendicular to the direction of wave propagation.
     1.      The particles of the medium vibrate parallel to the direction of wave propagation.
     2.      It travels producing Crests and Trough in medium.
     2.      It travels producing a series of Compression and Rarefaction in medium.
     3.      It can propagate only in solids and at the surface of liquids.
     3.      It can propagate in all types of medium: Solid, Liquid and Gas.
     4.      Transverse waves can be polarized.
     4.      Longitudinal waves cannot be polarized.
          
    
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