In addition to the phenomenon of interference, presented in the previous section, the waves present a wide range of behavior in different situations. The main ones are presented below.

## Reflection

It is when the wave strikes a surface of separation between two media and returns to the same medium.

The reflection of a mechanical wave at a fixed end is in reverse phase.

The reflection of a mechanical wave on the free end (mobile) occurs without phase inversion.

## Refraction

It is the phenomenon that occurs when a wave comes from one medium and penetrates into another medium. (This phenomenon is addressed deeply in the section: Optic | Refraction and Refractive Means )

## Diffraction

"Evading obstacles" and "Distinguishing particle from waves."

Diffraction is the distortion of linear propagation of waves that encounter obstacles, allowing the wave to circumvent them. The diffraction phenomenon is a characteristic of waves, particles do not diffract.

### Conditions of Sharp Perception

The diffraction phenomenon becomes increasingly clearer as the relationship between incident wavelength ( $$\lambda$$ ) and the size of the orifice or barrier $$d$$ becomes smaller than 1. $$\text{sharpness} = \frac{\lambda}{d}$$

### Application

Diffraction allows waves to bypass obstacles. Because of the diffraction it is possible to hear the sounds that are produced in a certain room from one house to another room.

## Polarization

It is a wave phenomenon typical of transverse waves. When this phenomenon occurs, the oscillations in the propagation medium are restricted to one plane.

## Other Phenomena

There are many other interesting phenomena in the wave. Here we will list a few more.

Dispersion
It is the phenomenon through which a wave is decomposed into the set of its constituent single waves.
Attenuation
Effective reduction of the intensity of a wave, which crosses a medium material and interacts with it.
Resonance
Phenomenon that occurs when a oscillating system is excited by a periodic external agent with a frequency identical to one of its own frequencies. In these conditions the transfer of energy from the external source to the system is maximum.