1. The particles of the medium vibrate simple harmonically along the direction of propagation of the wave.
2. All the particles have the same amplitude, frequency and time period.
3. There is a gradual phase difference between the successive particles.
4. All the particles vibrating in phase will be at a distance equal to nλ. Here n= 1,2,3 etc.
5. The velocity of the particle is maximum at their mean position and it is zero at their extreme positions.
6. At any instant, the arrangement of particles in the medium resembles a sine curve. In transverse progressive waves, at any instant all the particles arrange themselves along a series of crest and troughs in the form of a sine curve. In longitudinal waves, all the particles at every instant are in a straight line in the form of condensations and rarefactions.
7. When a progressive wave travels through a medium, there is a transfer of energy across the medium in the direction of propagation of the wave.