File Name: refraction and total internal reflection ppt to .zip
Learning Objectives. Book Reference : Pages
Report Download. The students Understand the phenomena of total internal reflectionAppreciate the applications of total internal reflection in various fields Develop logical reasoning abilityAre Exposed to the use of Total Internal Reflection in modern communication systems. What is Refraction? Refraction is the bending of light at the surface of separation between two transparent media when light passes from one medium to anotherLight bends towards the normal when it travels from a rarer to denser mediumLight bends away from the normal when it travels from a denser to rarer medium.
A common Physics lab is to sight through the long side of an isosceles triangle at a pin or other object held behind the opposite face. When done so, an unusual observation - a discrepant event - is observed. The diagram on the left below depicts the physical situation. A ray of light entered the face of the triangular block at a right angle to the boundary.
This ray of light passes across the boundary without refraction since it was incident along the normal recall the If I Were An Archer Fish page. The ray of light then travels in a straight line through the glass until it reaches the second boundary.
Now instead of transmitting across this boundary, all of the light seems to reflect off the boundary and transmit out the opposite face of the isosceles triangle. This discrepant event bothers many as they spend several minutes looking for the light to refract through the second boundary. Then finally, to their amazement, they looked through the third face of the block and clearly see the ray. What happened?
Why did light not refract through the second face? The phenomenon observed in this part of the lab is known as total internal reflection. Total internal reflection , or TIR as it is intimately called, is the reflection of the total amount of incident light at the boundary between two media. TIR is the topic of focus in Lesson 3. To understand total internal reflection, we will begin with a thought experiment.
Suppose that a laser beam is submerged in a tank of water don't do this at home and pointed upwards towards water-air boundary. Then suppose that the angle at which the beam is directed upwards is slowly altered, beginning with small angles of incidence and proceeding towards larger and larger angles of incidence.
What would be observed in such an experiment? If we understand the principles of boundary behavior, we would expect that we would observe both reflection and refraction. And indeed, that is what is observed mostly.
But that's not the only observation that we could make. We would also observe that the intensity of the reflected and refracted rays do not remain constant. At angle of incidence close to 0 degrees, most of the light energy is transmitted across the boundary and very little of it is reflected. As the angle is increased to greater and greater angles, we would begin to observe less refraction and more reflection. That is, as the angle of incidence is increased, the brightness of the refracted ray decreases and the brightness of the reflected ray increases.
Finally, we would observe that the angles of the reflection and refraction are not equal. Since the light waves would refract away from the normal a case of the SFA principle of refraction , the angle of refraction would be greater than the angle of incidence. And if this were the case, the angle of refraction would also be greater than the angle of reflection since the angles of reflection and incidence are the same.
As the angle of incidence is increased, the angle of refraction would eventually reach a degree angle. These principles are depicted in the diagram below.
The maximum possible angle of refraction is degrees. If you think about it a practice that always helps , you recognize that if the angle of refraction were greater than 90 degrees, then the refracted ray would lie on the incident side of the medium - that's just not possible.
So in the case of the laser beam in the water, there is some specific value for the angle of incidence we'll call it the critical angle that yields an angle of refraction of degrees. Any angle of incidence that is greater than Instead, when the angles of incidence is greater than When this happens, total internal reflection occurs. Total internal reflection TIR is the phenomenon that involves the reflection of all the incident light off the boundary.
TIR only takes place when both of the following two conditions are met:. Total internal reflection will not take place unless the incident light is traveling within the more optically dense medium towards the less optically dense medium.
TIR will happen for light traveling from water towards air, but it will not happen for light traveling from air towards water. TIR occurs because the angle of refraction reaches a degree angle before the angle of incidence reaches a degree angle. The only way for the angle of refraction to be greater than the angle of incidence is for light to bend away from the normal.
Since light only bends away from the normal when passing from a more dense medium into a less dense medium, then this would be a necessary condition for total internal reflection. Total internal reflection only occurs with large angles of incidence.
Question: How large is large? Answer: larger than the critical angle. As mentioned above, the critical angle for the water-air boundary is So for angles of incidence greater than But The actual value of the critical angle is dependent upon the two materials on either side of the boundary. For the crown glass-air boundary, the critical angle is For the diamond-air boundary, the critical angle is For the diamond-water boundary, the critical angle is The critical angle is different for different media.
In the next part of Lesson 3 , we will investigate how to determine the critical angle for any two materials. For now, let's internalize the idea that TIR can only occur if the angle of incidence is greater than the critical angle for the particular combination of materials.
Total internal reflection is often demonstrated in a Physics class through a variety of demonstrations. In one such demonstration, a beam of laser light is directed into a coiled plastic thing-a-ma jig. The plastic served as a light pipe , directing the light through the coils until it finally exits out the opposite end.
Once the light entered the plastic, it was in the more dense medium. Every time the light approached the plastic-air boundary, it is approaching at angles greater than the critical angle. The two conditions necessary for TIR are met, and all of the incident light at the plastic-air boundary stays internal to the plastic and undergoes reflection.
And with the room lights off, every student becomes quickly aware of the ancient truth that Physics is better than drugs. This demonstration helps to illustrate the principle by which optical fibers work. The use of a long strand of plastic or other material such as glass to pipe light from one end of the medium to the other is the basis for modern day use of optical fibers.
Optical fibers are used in communication systems and micro-surgeries. Since total internal reflection takes place within the fibers, no incident energy is ever lost due to the transmission of light across the boundary.
The intensity of the signal remains constant. Another common Physics demonstration involves the use of a large jug filled with water and a laser beam. The jug has a pea-sized hole drilled in its side such that when the cork is removed from the top of the jug, water begins to stream out the jug's side. The beam of laser light is then directed into the jug from the opposite side of the hole, through the water and into the falling stream.
The laser light exits the jug through the hole but is still in the water. As the stream of water begins to fall as a projectile along a parabolic path to the ground, the laser light becomes trapped within the water due to total internal reflection.
Being in the more dense medium water and heading towards a boundary with a less dense medium air , and being at angles of incidence greater than the critical angle, the light never leaves the stream of water. In fact, the stream of water acts as a light pipe to pipe the laser beam along its trajectory. Once more, students viewing the demonstration are convinced of the fact that Physics is better than drugs.
For each combination of media, which light ray A or B will undergo total internal reflection if the incident angle is gradually increased? Physics Tutorial. What Can Teachers Do My Cart Subscription Selection. Student Extras. Flickr Physics Photo. We Would Like to Suggest Why just read about it and when you could be interacting with it? Interact - that's exactly what you do when you use one of The Physics Classroom's Interactives. You can find it in the Physics Interactives section of our website.
Next Section: Critical Angle.
Whenever you look into a mirror or squint at sunlight glinting off a lake, you are seeing a reflection. When you look at the text in a book, you are actually seeing the light that is reflected from it. Large telescopes use reflections to form images of stars and other astronomical objects. In fact, the only way we can see an object that does not itself emit light is if that object reflects light. The law of reflection is illustrated in, which also shows how the angles are measured relative to the perpendicular to the surface at the point where the light ray strikes.
In this article, we shall study the phenomenon of total internal reflection and its applications. Total Internal Reflection of Light and its Explanation:. Let us consider a point source O in a denser medium Water. Let XY be the boundary separating the denser medium Water and the rarer medium Air. As the angle of incidence increases, the angle of refraction also increases. If the angle of incidence is more than i C , there is no refracted ray, the incident ray is completely reflected back in the water. This phenomenon is known as total internal reflection.
total internal elizabethsid.org - Free download as Powerpoint Presentation .ppt /.pptx), PDF File WHEN THE ANGLE OF REFRACTION IS 90 0.
A small part of the incident ray is reflected. For light traveling through a denser medium to a less dense medium, the angle of refraction,r in the less dense medium is larger than the angle of incidence,i in the denser medium. As the angle of incidence increases, the angle of refraction also increases. The angle of refraction reaches 90o before the angle on incidence does. At the instance, the refracted ray moves along the boundary.
What happen if i is bigger than c? The light is reflected internal at the surface in a medium glass. Its known as Total Internal Reflection. Normal State two conditions for total internal reflection could occur. Prism: Observe the changes of the ray when the angle of incidence ray in prism is increased.
Light does not escape as it travels along the fiber optics cable because it undergoes total internal reflection.
A common Physics lab is to sight through the long side of an isosceles triangle at a pin or other object held behind the opposite face. When done so, an unusual observation - a discrepant event - is observed. The diagram on the left below depicts the physical situation. A ray of light entered the face of the triangular block at a right angle to the boundary. This ray of light passes across the boundary without refraction since it was incident along the normal recall the If I Were An Archer Fish page. The ray of light then travels in a straight line through the glass until it reaches the second boundary. Now instead of transmitting across this boundary, all of the light seems to reflect off the boundary and transmit out the opposite face of the isosceles triangle.
Eighth Grade Grade 8 Light and Optics questions for your custom printable tests and worksheets. They travel all the way to the lateral geniculate nucleus. Beautiful PPT theme featuring science - fiber optics close-up modern computer backdrop and a mint green colored foreground Colorful PPT layouts enhanced with high tech - bunch of optical fibres dinamic backdrop and a navy blue colored foreground. Atmospheric Optics is the fancy name for light and colour in the atmosphere, such as rainbows, halos, shadows, and mirages. This is typically performed as a two dimensional fast discrete transform. We think of a glass window as transparent, but the thicker the glass gets, the less transparent it becomes due to impurities in the glass.
Боже всемилостивый, - прошептал Джабба. Камера вдруг повернулась к укрытию Халохота. Убийцы там уже не. Подъехал полицейский на мотоцикле. Женщина, наклонившаяся над умирающим, очевидно, услышала полицейскую сирену: она нервно оглянулась и потянула тучного господина за рукав, как бы торопя. Оба поспешили уйти. Камера снова показала Танкадо, его руку, упавшую на бездыханную грудь.
Нет. - Может быть, сказала, куда идет. - Нет.
Иногда даже, если жертва внушительной комплекции, она не убивает вовсе. - У него было больное сердце, - сказал Фонтейн. Смит поднял брови.
Уверяю вас, он стоит этих денег. Тут все без обмана. Он стоит десять раз по двадцать миллионов. - Увы, - сказал Нуматака, которому уже наскучило играть, - мы оба знаем, что Танкадо этого так не оставит. Подумайте о юридических последствиях.
Формула называется Цифровая крепость, говорилось в заметке, и доступна для ознакомления в Интернете. Программист намеревался выставить ее на аукционе и отдать тому, кто больше всех заплатит. Далее в заметке сообщалось, что, хотя алгоритм вызвал громадный интерес в Японии, несколько американских производителей программного обеспечения, прослышавших о Цифровой крепости, считают эту информацию нелепой - чем-то вроде обещания превратить свинец в золото. Формула, утверждают они, - это мистификация, к которой не следует относиться серьезно.
- Он положил руку ей на плечо. - Я никогда не послал бы туда Дэвида, если бы считал, что это связано хоть с малейшей опасностью. - Он улыбнулся.
А вы ищете проститутку. - Слово прозвучало как удар хлыста. - Но мой брат… - Сэр, если ваш брат целый день целовался в парке с девчонкой, то это значит, что она работает не в нашем агентстве. У нас очень строгие правила относительно контактов клиента и сопровождающего.
Стратмор холил и лелеял Сьюзан, оберегал. Он заслужил. И теперь наконец ее получит. Сьюзан будет искать защиту у него, поскольку ей негде больше будет ее найти.
- Мы кое-что упустили. ГЛАВА 13 Токуген Нуматака стоял у окна своего роскошного кабинета на верхнем этаже небоскреба и разглядывал завораживающие очертания Токио на фоне ярко-синего неба.
Сквозь туман она увидела Стратмора, который стоял внизу, на платформе. Прислонившись к перилам, он вглядывался в грохочущее нутро шахты ТРАНСТЕКСТА. - Коммандер! - позвала Сьюзан. Ответа не последовало.
Понятия не имею, о чем. - Лжец! - выкрикнула Сьюзан. - Я видела твою электронную почту. Хейл замер, потом повернул Сьюзан лицом к .