• The particles of the medium vibrate simple harmonically along the direction of
propagation of the wave.
• All the particles have the same amplitude, frequency and time period.
• There is a gradual phase difference between the successive particles.
• All the particles vibrating in phase will be at a distance equal to nA.. Here n = 1,2, 3, …
etc. It means the minimum distance between two particles vibrating in phase is equal to the wavelength-
• The velocity of the particles is maximum at their mean position and it is zero at their Extreme positions.
• When the particle moves in the same direction as the propagation of the wave, it is in a region of compression.
• When the particle moves in the direction opposite to the direction of propagation of the wave, it is in a region of rarefaction.
• When the particle is at the mean position, it is region of maximum compression and rarefaction.
• When the particle is at the extreme position, the medium around the particles has its
normal density , with compression on one side and rarefaction on the other.
• Due to the repeated periodic motion of the particles compressions and rarefactions are produced continuously. These compressions and rarefactions travel forward along the wave and transfer energy in the direction of propagation of the wave.