1. Waves are produced by vibrating systems.

2. Waves transfer energy. Waves that travel through a medium

__transfer energy without transferring matter.__

3. In transverse waves, the direction of waves propagation

__is perpendicular__to the direction of vibration of the particles.

Example: water waves, light waves and electromagnetic waves.

4. In longitudinal waves, the direction of wave propagation

__is parallel to the direction of vibration of the particles.__

Longitudinal waves

__need a medium to propagate.__This type of waves cannot propagate through a vacuum.

Example: a sound wave.

5. A wavefront is an imaginary line representing all parts of a wave in which particles are vibrating in the same phase and have the same distance from the source.

The direction of propagation of waves is always

__perpendicular to the wavefront.__

6. Amplitude, a, is the

__maximum displacement from the equilibrium position.__

7. Period, T, is the

__time required to make one complete oscillation.__

8. Frequency, f, is the

__number of complete oscillations made in one second.__

9. Wavelength, is defined as the distance between two consecutive points that are in phase.

( i ) For a transverse wave, wavelength can be measured as the distance from one crest and also the distance from one trough to the next trough.

(ii ) For a longitudinal wave, wavelength can be measured as the distance between

two consecutive compressions or two consecutive rarefactions.