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STEP 3: TO UNDERSTAND THE WAVES BEHAVIOR IN OPEN AND ENCLOSURE MEDIUMS

MEMBERS

FERNANDO ARBELAEZ COD: 79317435

Jorge Enrique Huertas Parada CC 79573243 Angelica Bravo CC 52663895 TUTOR DORIA LIZETH QUINTERO

UNIVERSIDAD NACIONAL ABIERTA Y A DISTANCIA UNAD 30 DE OCTUBRE DE 2018

TABLA DE CONTENIDO

OBJETIVES -

Understand the behavior of electromagnetic waves when influencing different means of propagation.

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Know the importance of Snell's law of refraction in different optical applications.

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Identify the modes of propagation of electromagnetic waves, establishing their advantages and disadvantages.

INTRODUCTIONS Telecommunications play an important role nowadays, the transmission of the waves represents the communication of people the whole world. Connectivity represents an increasing economic segment, and the study of different materials for the best transmission of the signal is fundamental for the future of society.

PARTNER CONTRIBUTION

FERNANDO ARBELAREZ PROBLEM 3 3. A laser that is inside a tank of water, shoots a ray of light upwards. If the laser is located h1 = 12cm under water. At what minimum horizontal distance d1 should the laser pointer shoot so that the beam does not come out of the water?

If we assume that the refractive index of water is n = 1.5 The critical angle for the water is calculated

With what you get a critical angle of

With this angle you get the trigonometric relationship between depth and distance

Development of the questions 1. Explain how the phenomenon of refraction and reflection in transmission systems could be used.

The Reflection and Refraction of Light. The reflection of the light is the change of direction of a ray or a wave in which a ray reaches the separation surface of two homogeneous media, that is to say the incident ray, is divided into another two, some of which returns to the first medium (Ray reflected) while the other propagates through the second medium (Refracted ray). Common examples of the reflection of light is the sound and the waves in the water. Application of the Reflection of light in the field of communications The application of optical fiber in communications has resulted in an explosion in information. Optical fiber has a greater bandwidth than copper wire, which means that more information can be transmitted over a fixed period of time. This increase in the capacity to transport information provides new and important possibilities, including interactive television and cable channel selections, in three thousand applications.

Even though it is easy to perceive how optical fiber is changing the world around us, it may surprise us to know that this ability to transmit information depends mainly on a single physical phenomenon: total internal reflection. Total internal reflection is the result of the internal passage of light through a medium to meet a second medium of lower optical density. An optical fiber consists of two such means.

2. Explain Snell's law, the critical angle and the practical applications where it could be used.

Huygens principle. Reflection and Refraction Snell's Law As we already know, a wave is an energy transport through a periodic movement, this implies a displacement and therefore dynamic characteristics.

In a Cartesian coordinate axis where we distinguish two variables (x and y), the "X" axis always receives the name of the abscissa axis while the "Y" will be known as normal this time Let's suppose the following situation; a wave hits a surface that separates two different media (n1 and n2) with a certain angle, this is called angle of incidence, the first medium can be air and the second, water, for example. When this occurs, two phenomena occur simultaneously; one of refraction and one of reflection. From reflection we only have to point out that when a wave hits a surface it is reflected at an angle equal to that of incidence on the other side of the normal. We can define refraction as the change of direction that a wave experiences when passing from one medium to another and if we want to go deeper we can add that this change is produced by the difference in the speed of propagation in both media. That is, for example in the typical case of light, when it spreads through the air it does so at a different speed than in water, in glass, in general in any material or surface, this is due to what is known as refractive index.

The refractive index is nothing more than the relationship between the speed of light in vacuum and the speed in another medium, therefore: With this relation, in a typical problem of selectivity and in particular of optics we can determine the refractive index of the second medium through which the light propagates and the speed of the same in said medium since "c" (speed of light) in a vacuum) is a constant (3x10 ^ 8 m / s)

Later, with the law of Snell we can explain the why of this but theoretically we deduce that when a wave passes from a faster medium to a slower one (with a higher refractive index) it approaches normal, whereas on the contrary it goes from a slower medium to a faster one (with a lower refractive index) it moves away, until it reaches the maximum "opening" or possible angle and the wave propagates not through the second medium but through the separation surface of both (axis X) This phenomenon is called Total Reflection Applications of Lenz's law Alternators are devices that generate alternating electric currents, hence their name. They consist of two essential elements: the rotor, which causes the rotation of the assembly, and the stator, which surrounds the previous one and is in charge of rotating around its axis. These alternators generate an alternating current with the purpose of being used for motors, generating at the same time, mechanical energy starting from the electrical energy; with only the connection of the brushes of an alternator with another generator. This induces a reorientation and an indefinite rotation of the turn of the second alternator while a current is supplied. 3. Explain the physics behind the lenses for optical diseases. Eye diseases and corrective lenses • Focal mono lenses The mono focal lenses offer a more natural vision and can correct differences in near vision as this is distorted, it also differentiates in the distant vision since it perceives very close objects but distorts the near ones.

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Bifocal lenses

Bifocal lenses are lenses that combine more than one prescription on the same lens. These glasses are necessary to correct the sight of a person to whom a single graduation does not allow him to see correctly at all distances. They are lenses to see correctly at different distances. These lenses have a differentiated cut in the middle of the glass that marks the two different graduations. The upper part of the lens serves to look "from far" and the lower part serves to see "up close". Contact lenses Also known as contact lenses, are corrective or cosmetic lenses that are placed in the eye, specifically on the tear layer that cares and lubricates the cornea. These lenses are sanitary products and must meet all of these requirements.

They are thin transparent plastic discs used to correct: myopia, hyperopia, astigmatism and presbyopia.

• Converging lenses They are thicker in the center than at the ends. They are represented schematically with a line with two arrowheads at the ends. And they concentrate (they converge) at a point the rays of light that cross them. At this point it is called focus (F) and the separation between it and the lens is known as focal distance (f).

• Divergent lenses They are thinner in the central part than in the ends. They are represented schematically by a straight line ending in two inverted arrowheads. They are those that concentrate in a point the rays of light that reach them, parallel to each other • Cylindrical lenses With this type of lens the astigmatism is corrected, compensating the lengthening of the points of light that occur in this refractive defect. Just as spherical lenses are sections of a sphere, cylindrical lenses are sections of a cylinder. Also like spherical lenses, cylindrical lenses can be convergent or positive and divergent or negative. EYE DISEASES •

Waterfalls

A cataract is the loss of transparency of the lens of the eye and this causes decreased vision. The most common type of cataract is related to age. Symptoms of a cataract: -In the beginning a little blurred vision. -The sunlight or light bulbs look brighter and this cause glare. - Difficulty seeing at night. •

Colour blindness

It is a genetic defect that consists in the impossibility of distinguishing the colors (dyschromatopsia). Although the confusion of colors between a colorblind and another can be totally different, even in members belonging to the same family, it is very common to confuse green and red; however, they can see more nuances of violet than people with normal vision and are able to distinguish objects camouflaged • Hypermetropia It is an ocular defect that consists of the rays of light that impinge on the eye coming from infinity, focusing on a point located behind the retina instead of the retina itself as it would be normal. The consequence is that the image is blurred and therefore there may be a lack of visual acuity. It can be treated through the use of glasses with convex or positive corrective lenses. It is also possible to use contact lenses for hyperopia, contact lenses, surgery of the cornea with laser. • Presbyopia Also called tired eyesight, it is a defect or imperfection of the sight that consists in the diminution of the focusing capacity of the eye. As a consequence, there is difficulty in seeing clearly the nearby objects. The treatment of presbyopia by surgery consists of an operation in which the lens is removed and replaced by a multifocal intraocular lens. As in any surgery, there may be complications that in this case are very similar to those of the cataract intervention.

• Astigmatism It is an ocular state that usually comes from a problem in the curvature of the cornea, which prevents the clear focus of objects both far and near. The cornea, which is a spherical surface, suffers a flattening at its poles, which produces different radii of curvature in the axis of the eye, therefore when light reaches the eye, specifically in the cornea, the image obtained is little sharp and distorted. It is corrected with cylindrical lenses. • Myopia It is a refractive defect. In a myopic eye, the image is focused in front of the retina. It is corrected with the diverging lens.

4. What is the importance of the refractive index? In a vacuum, the light propagates at a speed of C = 3.0 × 108 while in any other medium, it propagates more slowly. The relationship between "C" and the speed of light in any other medium is called the refractive index of that material, represented as "n". The refractive index is governed by Snell's law, by which, this property corresponds to the division between the sinuses of the angles of incidence (the angle between the ray in the first medium and the perpendicular in the dividing surface) and of refraction (angle corresponding to the second medium) n = sin (Ø1) / sin (Ø2). The determination of the Refraction Index is influenced by the temperature and the wavelength of the emitted light. Under controlled measurement conditions, it is a constant property for a medium and allows determining the purity of a substance or quantifying a given compound in binary mixtures of known constituents. Refractometers are important instruments in the food industry, since they are used in the analysis of liquid products and in the control of operations during the processing of various foods: milk and its derivatives (condensed, evaporated, dairy products ...), fruits, juices , jams, honey, sauces (ketchup, mustard, soups ...), manufacture and refining of sugar, pastries and pastries.

5. Is it possible for a single beam of light to be refracted in several beans? Explain According to the definition the refraction of the light happens when it passes from a transparent medium with a certain refractive index to another, also transparent, with a different one, I consider that a bean contains an internal composition that is not very transparent and could not be refracted to another bean. There could be reflection and lightning jump from one bean to another.

6. How is it possible to use the Brewster angle in practical applications? According to the definition when a beam of light impinges with the Brewster angle, the component of the polarization parallel to the plane of incidence is annulled in the reflected beam. For this reason, the beam that we see reflected

has a linear polarization, just in the direction perpendicular to the plane of incidence, regardless of the type of polarization of the incident beam.

The Brewster Angle Microscope allows us the direct visualization of the formation of mono molecular layers in real time in the water-air interface, the characterization of molecular films through BAM is recorded through images of the formation "in situ", evaluates reproducibility, homogeneity and possible morphological defects. A BAM allows the visualization of Langmuir mono molecular layers or the absorbance of the film at the air-water interface. When the beam of light (laser) sticks on the surface the image of the molecule is reflected to the detector, changes in the structure and formation of the mono layer can be observed in real time during the measurements.

Collaborative work Design an Excel workbook that uses Snell's law and provide an incident angle for four different precious materials; Return the refraction angle and let us know if it is genuine.

https://www.foro3d.com/attachments/104931d1243286288-valores-del-indicede-refraccion-refraccion.jpg?s=cb7b31834ac0acb030b6587b7dec98bb TABLA DE INDICES DE REFRACCION AIRE(n1) ESMERALDA(n2) TOPACIO ROSA(n2) OJO DE TIGRE(n2) MARFIL(n2) índice n1 índice n2 ángulo (teta)i Angulo refracción

1 1.576 1.62 1.544 1.54

PASOS PARA OBTENER EL ANGULO DE REFRACCION Primero: indique el índice de refracción n1 Segundo: indique el índice de refracción n2(Según su preferenci Tercero: indique el ángulo de incidencia (teta)i Cuarto : Haga lectura de Angulo de refracción en grados

#¡DIV/0!

PARTNER CONTRIBUTION

Jorge Enrique Huertas Parada Problem 1

When red light in vacuum is incident at the Brewster angle on a certain glass slab, the angle of refraction is glass and (b) the Brewster angle? // //

Vacuum / // / //

n1=1

Glass n2=?

Ley de Snell

What are (a) the index of refraction of the

PARTNER CONTRIBUTION Angelica Bravo

1. Explain how refraction and reflection phenomenon could be used in transmission systems.

Because, the phenomenon optical are easily restricted to limited space, in this case, the transmission of the light is the medium whereby, the information travel, and in the nature the constant of light is the more rapid. The used of the phenomenon waves proprieties is the form more practical and economic of the travel of information.

If the proprieties are known the transmission is only the used of reflection of the light, and the refraction of the light is the information loss.

2. Explain the Snell law, the critical angle and practical applications where it could be used. The law of Snell- Descarte is an equation that relation the ray incident in the limit of surface, the condition are: The ray is the same plane, the reflection and refraction depend of the velocity of the mediums.

The law is:





if

then

the angle

If

and then

is more closed of the normal that the incident.

then

the ray is reflected and reflected.

3. Explain the physics behind lenses for optical diseases.

4. What is the importance of the index of refraction?

The index of refraction is more important, because, the relation between the index of the mediums is the condition for the reflection and the reflection of the incident ray. 5. Is it possible that a single light beam be refracted into several beans? Explain. Yes, it is depended of the relation between the mediums, if the velocity is minus in the n3