• Undulatory
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• Waves
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• Waves phenomena

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. Reflection of a one-dimensional mechanical wave. a) On the left part of the figure, we present what happens with a pulse wave which is being reflected by a fixed end of the rope (imagine that the rope is tied to a wooden trunk). b) On the right part, this is what happens with a pulse reflected by an end that can move vertically (imagine that the rope is attached to a ring which can slide vertically on a wooden trunk).

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 ) Phenomenon of refraction. The figure illustrates a wave (the lines represent the ridges of the wave) propagating in a fluid in a vessel. The dark blue color is a deeper region and the lighter a shallower region. The wave, when passing from one region to another, suffers a change in its speed, and therefore in their direction.

## 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. Illustration of the diffraction phenomenon. The lines illustrate the peaks of waves that propagate in a fluid, the brown rectangles represent wooden obstacles. Depending on the position of the obstacles, the wave diffracts in different ways.

## 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. Illustration of a light being polarized. When going through a polarizer, vertically, only the vertical oscillations (blue wave) are transmitted. Once polarized vertically, the light cannot pass through a horizontal polarizer. In this case, the final light intensity will depend on the angle between the polarizers.

## 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. # STUDY PHYSICS ANYTIME ANYWHERE Dynamic Exams Differentiated Content Top approval rate