Answer:
Waves are periodic disturbance of a medium that transmit carrying energy but not matter.
Depending on which direction the particles oscillate, waves are divided into two types:
- Transverse waves: in these waves, the oscillations occur in a direction perpendicular to the direction of motion of the wave. Examples of transverse waves are the vibrations in a guitar string.
- Longitudinal waves: in these waves, the oscillations occur back and forth along the direction of motion of the wave. Examples of longitudinal waves are sound waves.
As a result, amplitude and wavelength are measured differently in the two types of waves. In particular:
- The amplitude in a transverse wave is measured as the distance between the equilibrium position and the maximum displacement of a particle in the wave, in the direction perpendicular to the motion of the wave. On the other hand, in a longidutinal wave this distance is measured as the maximum displacement along the direction of propagation of the wave.
- The wavelength in a transverse wave is measured as the distance between two consecutive crests (points of maximum displacement) of the wave. For a longitudinal waves, there exist no crests, but regions of highest density of the particles (compressions) and of lowest density of the particles (rarefactions), so the wavelength is measured as the distance between two consecutive regions of compressions (or rarefactions).
