CONCEPTS

# What is a wave?

We explain what a wave is and the types of wave that exist. In addition, what are its parts and how this phenomenon can spread.

1. ### What is a wave?

In physics , it is known as the wave to the propagation of energy (and not of mass) through space , by disturbing some of its physical properties, such as density , pressure , electric field or magnetic field. This phenomenon can occur in an empty space or in one that contains matter ( air , water , earth, etc.).

The waves are produced as a result of oscillations and vibrations of matter , propagating in time as described by the theory of waves, branch of physics responsible for understanding this phenomenon, very common in the universe . The propagation of waves is one of the fundamental physical phenomena .

According to the origin of the waves or the nature of the medium through which they propagate, then, the effects of their appearance and the characteristics they possess will depend. Thus, we can talk about light waves , sound, etc., each with physical properties and a different frequency , depending on how resistant or not the medium for its propagation and how much energy they carry.

Some waves, such as sound waves, cannot be transported in a vacuum. They therefore require a present physical environment. Others, such as microwaves, can do it perfectly and quickly: this is how artificial satellites that send information to Earth operate.

1. ### Wave types

We can classify the waves according to different criteria, such as:
According to the medium in which they  propagate . According to the medium we can distinguish between:

• Mechanical waves . Those that require an elastic medium ( liquid , gaseous or solid ) and certain conditions of temperature and pressure, to propagate effectively. Example: sound waves.
• Electromagnetic waves . Those that do not require a medium, because they can be perfectly propagated in a vacuum, since they are due to cyclic variations of the electromagnetic field of matter. Example: the light.
• Gravitational waves . Recently confirmed by science, they are alterations of space-time where the reality of the universe resides.

According to its periodicity . We can talk about periodic waves (it presents repetitive cycles in its production) or non-periodic (its cycles are irregular).

According to your address . They may be one-dimensional (they propagate through a single space dimension), two-dimensional (they propagate through two dimensions and are usually also called  superficial ) and three-dimensional (they propagate in three dimensions and are usually called  spherical ).

According to the movement of the medium . They can be longitudinal waves (the particles of the medium move in the same direction in which the wave propagates) or transverse waves (the particles vibrate perpendicularly to the direction of propagation of the wave).

1. ### Parts of a wave

A wave is made up of the following parts:

• Cresta . The maximum point in the undulation, that is, in the wavelength: the furthest point of the rest it reaches.
• Period . Represented with the letter T, is the time it takes for the wave to go from its crest to the next, that is, to repeat itself.
• Amplitude . Represented with the letter A, it measures the vertical distance between the crest and the midpoint of the wave, halfway to rest. This measure can grow or decrease over time depending on the case.
• Frequency . Represented with the letter f, it is the number of times the wave is repeated in a given unit of time, which is why it is calculated according to the formula f = 1 / T.
• Valley . The opposite of the crest: the point closest to the rest of the wave.
• Wavelength . Represented by the symbol λ (lamda), it is the distance between two consecutive ridges of the undulation.
• I cycle . This is called a complete undulation, from beginning to end.
1. ### How do waves spread?

As mentioned, the waves usually need a material medium to propagate, although some can do it perfectly in a vacuum. This depends on the nature of the wave.

For example, electromagnetic waves do not require a material medium to propagate , so they are a form of radiation. This is because they constitute alterations in the electric and magnetic fields of the particles, and they travel at very high speeds ( the speed of light , for example, 300,000 km / s).

On the other hand, mechanical waves require a physical means to propagate , such as water, a metal, air from the atmosphere or other elements and surfaces, provided they are capable of transmitting a ripple, as occurs in tremors or on the surface of the water when we throw a stone into a pond.