While there are many components used in building up a fibre optic link fiber optic link, the fibre optic cabling is obviously the key element. A level physics the course physics is a subject of enormous breadth. Fourier transforms are used extensively in this course beginning with chapter7. It encompasses the whole of the physical world from fundamental particles to supermassive black holes, from the beginning of time to the ultimate fate of the universe. Wider fibre cores produce a longer path for any given photon to travel as they bounce back and forth along the length of the cable. Although not apparent, fiber optics plays a very significant role in our daily lives.
Physics as optical fibres question please help the student room. Also relevant to the p3 topic 1 content of gcse course. Uses of optical fibres include communications and medical endoscopes. Optical communications became a possibility after the first lasers were developed in the 1960s. Light propagates inside the fibre, which is made of glass which has a higher refractive index than the air outside. Optical fibers are therefore classified as stepindex or gradedindex, and multimode or singlemode, as illustrated in fig. This means that light shone into the core at an angle greater than the critical angle will total internally reflect at the boundary between the core and the cladding. Jun 03, 20 this website and its content is subject to our terms and conditions. Optical fibre typically consists of a core of high refractive index surrounded by cladding with a lower refractive index. If the direction of a ray of light is reversed it will follow same path, but in the opposite direction loud notes have more energy than quiet notes and therefore have a larger amplitude high pitch notes produces more waves per second than low pitch notes and therefore have. This is has a fine glass core and it is surrounded by a cladding of glass with a lower refractive index than the core.
The difference between the refractive indices of core and cladding is also large compared to the single mode fibers. The diagram below shows a straight section of optical fibre, but the cable can bend and the light will continue to travel down the fibre, as long as the critical angle is achieved. Optical fibres optical fibres use tir to send light pulses down glass fibres. These are a bit old now but the questions are perfectly valid if you want to try a question a day in the run up to end of year exams or your actual exams. Light getting in at one end undergoes repeated total internal reflection, even when the fibre is. In multi mode optical fibers many mummer of modes of propagation are possible. Comprehensive revision notes for gcse exams for physics, chemistry, biology. If light is propagating from a more dense to a less dense medium in the optical sense, i. At the time of publication gec was the largest manufacturer of electrical and electronic products in the united kingdom, and was one of the biggest companies in the world in this field. Below we have list all the links as per the modules. Optical fibres the critical angle and optical fibres. Optical fibres made from highdensity glass can carry light signals long. Tes global ltd is registered in england company no 02017289 with its registered office at 26 red lion square london wc1r 4hq. An optical fibre is a thin rod of highquality glass.
Total internal reflection, geometrical optics from alevel physics. In the telecommunication field they are used as an alternative signal carrier to copper wires in the telephone system. Alevel physics revision notes, videos and more for aqa. Optical fibres optical fibre typically consists of a core of high refractive index surrounded by cladding with a lower refractive index. Notes on optical fibres and fibre bundles introduction this note has been prepared with the intention of putting of summarising salient facts about optical fibres. Whenever refraction occurs, as light passes from one medium to another a small amount of. Optical fibres are used extensively in the field of telecommunications and medicine. The core and cladding have different refractive indices, with the core having a refractive index of n1, and the cladding having a refractive index of n2. A fiberoptic cable is composed of two concentric layers, called the core and the cladding, as illustrated in figure 31. Plane polarised waves are emitted by the transmitter and if you measure the angle of the filter and record the intensity at the receiver you can then show maluss law in the lab. A level physics revision notes, videos and more for ocr. Here you can download the optical fiber communication vtu notes pdf ofc pdf vtu of as per vtu syllabus.
Dec 30, 2016 powerpoint covering the content for several lessons of the aqa as level physics waves topic. The theory covered includes total internal reflection and the significance of the critical angle, the stru. In case of in multi mode fiber the diameter of core is 50 to 200 micrometers. When we make longdistance or international telephone calls or browse through. Light is totally internally reflected down the fibre at the boundary of the two media.
They are used to carrier digital signals in the form of light pulses over long distances. Also offering past papers and exam questions by topic for aqa, edexcel and ocr. It has a central core in which the light is guided, embedded in an outer cladding of slightly lower refractive index fig. The first itut handbook related to optical fibres, optical fibres for telecommunications, was published in 1984, and several others have been produced over the years. Fiber optics are very long, thin glass fibers that transfer informationbearing light from one place to another, but that may not be in direct sight of each other. There are many uses for tir starting from the simple replacement of mirrors with prisms in periscopes to the complicated world of fibre optics. While a mechanical wave exists in a medium which on deformation is capable of. Fibre optic cables allow very high bandwidth indeed, and. Of course the selection of the characteristics presented is inevitably limited and biased. However these systems were limited in bandwidth and optical systems were investigated. Medical physics this teaching guide provides background material for teachers preparing students for the medical physics option of our alevel physics specification 7408.
Besides imaging, fiberoptic networks are probably the largest application of optics. Aqa as level physics and gcse p3 waves tir and optical. Optical fibres the refractive index of the glass fibre the core must be higher than that of the plastic coating the cladding for total internal reflection to occur this type of optical fibre is called a stepindex fibre because the refractive index increases in a step from the air on the outside, to the much higher value of the cladding, to the even higher value of the core. Optical fibres are also more difficult to join principle of reversibility. Fibre optics optical fibres utilise total internal reflection at the boundaries of the fibre to carry information digitally in the form of light. The presentation below is su ciently comprehensive for the student who encounters fourier. Limited since there are numerous textbooks and websites which are available for more.
Optical fibre has a number of advantages over copper wire. As a result of recent technological advances in fabrication, light can be guided through 1 km of glass fiber with a loss as low as 0. The type of optical fibre you need to know about are stepindex optical fibres. Apr 30, 2010 optical fibers are widely used in fiberoptic communications, which permits transmission over longer distances and at higher bandwidths data rates than other forms of communications. A level physics revision notes, videos and more for aqa. Mar 29, 2015 the optical fibre is surrounded at the outer layer by the buffer coating which is a plastic coating that protects the fibre from damage and moisture. This is where light would refract form one fibre into the next. Waves a wave is a disturbance that pppg gropagates through space and time, usually with transferrance of energy. This chapter emphasizes the nature of optical modes and their group velocities in stepindex and gradedindex fibers.
The idea lingers in the term optical density, a property of a material that the index of refraction measures. Optical fiber communication vtu notes pdf ofc pdf vtu. This video shows how you can use a microwave transmitter and receiver to investigate the polarisation of microwaves. Physics revision site recommended to teachers as a resource by aqa, ocr and edexcel examination boards also recommended by bbc bytesize winner of the iop web awards 2010 cyberphysics a physics revision aide for students at ks3 sats, ks4 gcse and ks5 a and as level. The key physics point to make is that the use of an optical fibre enables video.
Refractive index, total internal reflection, optical fibres pass my. The course is challenging and involves a fair amount of mathematics at times but it is. This association for science education ase publication about optical fibres was developed in association with the general electric company gec. It is an honour to present you with the latest version, which is another example of how itut is bridging the standardization gap between developed and developing nations. Equations for the characteristics of fiberoptic fibers dummies.
Refraction calculations and total internal reflection s. Abstract the intended application of our different types of dispersions in an optical fiber. If optical fibres touch each other, crosstalk can occur. The optical fibre is surrounded at the outer layer by the buffer coating which is a plastic coating that protects the fibre from damage and moisture. Since attenuation is a function of distance travelled, a wider cable produces a greater attenuation as the incidence angle increases for any given photon. When the effect of lenses or mirrors on paths, we consider the drawing of diagrams using lig. Answer notes marks 1 a 3 or more correct lines 2 marks 2 any two correct lines 1 mark notes about the total internal reflection of light right or wrong the angle of incidence equals the angle of reflection light changes speed when it is internally reflected every ray entering the semicircular glass block is.
In this report we discuss about the optical fiber and its advantages, theory and principles of the fiber optics, fiber geometry, types of optical fiber, different parameters and characteristics of fiber are also explained. Alevel physics revision notes, videos and more for ocr. The physics behind fiber optics fiberoptic technologies. This is a useful way of measuring the refractive index for a material. An optical fiber is a cylindrical dielectric waveguide made of lowloss materials such as silica glass. Longitudinal waves are waves in which the motion of the individual particles of the medium is in a direction that is parallel to the direction of energy transport. It provides more detail on specification topics that teachers may not be familiar with and should be used alongside the specification. Feb 02, 2015 22 videos play all everything about waves a level physics physics online refraction and snells law a level physics duration. The next piece of the jigsaw fell into place when the first optical fibers with a sufficiently low loss for communications purposes were developed in the 1970s. Wave theory of light is used to explain the reflection and refraction of light.
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