What Is Fibre Optics
WHAT IS FIBRE OPTICS? To put it simply, fibre optics is a technology whereby a signal like video, data or voice, is concentrated on a light beam and sent down a glass tube over large distances, with very little distortion and loss. The principles of fibre optics are simple and easy to understand. All of us have seen the "broken straw" effect in a glass of water. When light travels from air to a denser medium, like glass for example, the light slows down by a factor equal to the optical index of the material and this slow down in speed results in bending of the light. As shown in the example when we see an object from underwater, the object is not in the actual position as we think because light bends travelling from water to air. When this angle of entry is increased, there would come a stage when the light is reflected back into the same medium, as shown in ray 3. This angle is called the angle of Total Reflection. Fibre Optics uses this simple principle for transmission. The core of the fibre optics cable, which is made of glass, has a higher index of refraction than the index of the cladding, which covers this core. So when light is injected into the glass core at the correct angle, it will reflect back from the surface and continue doing this in its forward direction of travel. In other words the light cannot "escape" from the fibre. COMPONENTS OF A FIBRE OPTICS
Investigation of the response of a microphone / loudspeaker over a range of frequencies
Investigation of the response of a microphone/loudspeaker over a range of frequencies Aim & Hypothesis To become proficient with using a signal generator and a Cathode Ray Oscilloscope (CRO.) Also, to investigate how the amplitude of a signal from a microphone varies as the frequency of a fixed amplitude signal applied to the loudspeaker varies, (between 100Hz and 1000Hz.) Safety RISK ASSESSMENT - LEVEL ONE This experiment does not carry many hazards. Bags and coats will be moved out of the way to ensure that no one will trip over them. The only other potential danger is as a result of using mains operated equipment. I will not be using the equipment near any water, taps etc. I will do a visual check on the equipment before use (not fraying or lose wires, etc.) Variables Independent Variable: Frequency (Hz) Dependent Variable: Amplitude (mV) I will be using the signal generator to alter the frequency being produced - therefore this will be the independent variable. This will alter the amplitude of the wave being shown on the CRO so this is the independent variable. I have used the same equipment throughout the experiment in order to ensure a fair test. Diagram Method The apparatus was set up as shown on the previous page. Firstly I did three 'checks' to ensure that (to check if they are properly calibrated.): * The amplitude of the signal remains constant *
Graphs illustrating variants of y = sin x.
Part 1 Graph 1 Graph 1 is showing y = sin x. Now lets look at the graphs of y = 2sin x ; y = ? sin x ; y = 5sin x y =2sin x Graph 2 y = 1/3sin x Graph 3 y = 5sin x Graph 4 If we compare graphs 2, 3 and 4 we can see that the number in front of sin (this number is called A) changes the vertical compression of the wave. When A<1 then the graph vertically compresses or amplitude becomes lower (graph 3) and when A>1 then graph expands vertically or amplitude becomes higher (graphs 2 and 4). If the number is 2, then the wave doubles vertically and when the number is 1/2 it compress by half. The comparison is of course made with the graph of sin x. Now let us see what happens when we make the equation negative by putting a minus sign in front of sin. By doing this we are taking A<0. Graph 5 Graph 5 shows us that the wave flips around when A is negative. So we can conclude that when A<0 the wave will always be upside down From investigating graphs of y = Asin x, we can conclude that when the A is less than 1 then the wave compresses vertically and when A is greater than 1 the wave expands vertically. If A is less than 0, then the whole wave flips upside down. To conclude we can say that A will equal to the number on the y-axis because
An investigation into the factors affecting the frequency of a standing wave
An investigation into the factors affecting the frequency of a standing wave Introduction There are several ways in which you can control the pitch (frequency) of a note produced by a string. A string with 2 fixed ends (called nodes) can produce different standing waves. The lowest frequency standing wave that can be produced has a wavelength ? where ? = 2l (l = length of string) This is related to the frequency ƒ of oscillation by the wave equation V = ƒ? Where V is the speed of transverse waves traveling along the string. You can therefore deduct that ƒ = v/? = v/2l ƒ therefore should be inversely proportional to the length of the string, i.e. the shorter the string, the higher the note. The frequency will also depend on the tension and the mass per unit length of the string, as they affect the speed of transverse waves traveling along the string. The greater the tension, the greater the speed, and the heavier the string, the lower the speed. This becomes important in this investigation because if the experiment is to be fair, then the two other factors affecting the frequency must be kept constant for the results to be accurate. I have decided to investigate the effect that altering the length of string along which the wave travels. From the above equations, I would expect the frequency to be inversely proportional to the length of string, as you would
Find the critical angle and refractive index for plastic using a graphical treatment for my results.
Investigating Refraction Aim: Find the critical angle and refractive index for plastic using a graphical treatment for my results. Introduction: The Refractive Index is how the much a material bends the light. In this experiment I will be looking at the how much the angle of incidence gets refracted and I will multiply my results by sine. I will plot a graph from my results and, using a line of best fit, I will calculate the size of the angle of incidence in order for the refracted angle to be equal to 900 (critical angle). I will then calculate the refractive index by using Sine I and Sine R. I will be looking at light going from glass to air (from a dense medium to a lighter one). Theory: Incident ray: Ray of light before refraction. Angle of refraction (R): Angle between refracted ray and normal at point of incidence. Angle of incidence (I): Angle between incidence ray and normal at point of incidence. Point of incidence: Point at which incident ray meets boundary and becomes refracted ray. Critical angle: The particular angle of incidence of a ray hitting a less dense medium, which results in it being refracted at 900 to the normal. Normal: A line at right angles to boundary through chosen points. There are two main laws of refraction of light: 1. The refracted ray lies in the same plane as the incident ray and normal at the point of incidence. 2. (Snell's law). The
Is Sunbathing Good?
Is Sunbathing Good For You? Tanushri Gukhool 10a Mr Terry Contents page Introduction.................................................................................pg2 Ultraviolet radiation.....................................................................pg2 The sun can be good for you.........................................................pg2 The sun can be bad for you..........................................................pg2 Sun beds..................................................................................pg3 How the Skin Tans.....................................................................pg3 UV and your health.....................................................................pg4 UV sessions..............................................................................pg4 Risks........................................................................................pg5 Who is most at risk?....................................................................pg6 Health benefits...........................................................................pg6 Tanning fakes............................................................................pg7 Tanning myths...........................................................................pg7 Conclusion................................................................................pg8
How does the number of coils on an electromagnet affect its strength?
Science Coursework: How does the number of coils on an electromagnet affect its strength? Aim: - To establish whether a variation in the number of coils will affect an electromagnet's strength. Scientific Knowledge: - The concept of electromagnets is fairly simple. An iron nail wrapped in a series of coils of insulated wire and then connected to a battery, will enable the nail to pick up paper clips. This is because the current emitted from the battery to the coils magnetises the nail. This is known as an electromagnet. The current passing through an electromagnet produces a magnetic field. Therefore, the more turns of the coil you have, the greater the magnetic field and the stronger the electromagnet. This will mean more paper clips being picked up by the nail. The strength of an electromagnet can also be altered by varying the current or voltage. The more induced voltage, the stronger the electromagnet. An alternative way to strengthen an electromagnet is to replace the core with a "soft" iron core. Prediction: - An increase in the number of coils applied to the iron nail will cause an increase in the number of paperclips being picked up. (a positive correlation between the two variables) This prediction derived from the scientific knowledge above - 'Therefore, the more turns of the coil you have, the greater the magnetic field and the stronger the
Mobile Phone case study
Gary Thompson Monday 30th March 2009 Science Case Study: Do Mobile phones affect our health? - Page 3 - Page 4/5 - Page 6 - Page 7 - Page 7 - Page 8 Introduction My coursework piece for physics had to be based on the topic of the effects of radiation emitted from mobile phones. Therefore, I began my case study by researching people's opinions on the subject. In this case study, I plan to investigate both the arguments for and against my question: "Does use of mobile phones adversely affect our health?" I will do this by using a number of sources and by researching evidence that back up my own ideas. In addition to this, I will conclude this case study with a final look at my opinion. Scientific Theory Mobile phones work using cells. That is where the American term "cell phone" derives from. Each cell has a base station as its centre. The base station sends and receives calls from the phone. There are three different types of base station; Macrocells, Microcells and Picocells. Macrocells are the largest type of base stations and provide the main coverage for mobile phone networks. Its antennas can be mounted on ground-based masts, rooftops or other structures and must be high enough to avoid obstruction. Macrocells provide radio coverage over different distances, depending on the frequency used, the number of calls being made and the surrounding environment.
Experiment to investigate the relationship between speed and depth for a water wave.
Physics Coursework Aim: Experiment to investigate the relationship between speed and depth for a water wave. I predict that the greater the depth of water the faster a water wave would travel. Speed=distance travelled / time Prediction: As I explained earlier, the greater the depth of water the faster a water wave would travel. The angle of the guttering is a major factor in this as changing the angle would make the guttering unlevel and will slow down the wave therefore making the experiment unfair. Apparatus: The equipment I need to carry out the work and to obtain my results is: · A length of gutter · Water · 250cm3 Beaker · Metre Ruler · 30cm ruler · Retort stand · Clamp · String · A wooden block · Stopwatch Diagram: Preliminary Work: Preliminary work is the work that is done beforehand for you to know that the experiment is going to work. It is a way for the person carrying out the experiment to know that it has been set up correctly when the actual experiment begins. For my preliminary work, I did the experiment and tested that a wave would be able to be created. The preliminary work brought up the problem of how high the wooden block should be held up before it is swung into the water, it was decided that it should be swung from about 4cm above the bottom of the guttering. Safety Precautions: Even though safety is a virtue the
Optics - the human eye and coomon defects
Eye Defects Vision:- The mammalian eye could be regarded as a miracle of evolution. In order to produce an image the eye has to act as an Optical refracting System (to focus a sharp image) and a Photo Detector (to analyse the image and send information to the brain). At the front of the eye is the optical system, made up of the transparent curved Cornea and the adjustable biconvex Lens. The photo detector is the layer of light-sensitive cells at the back of the eye, called the Retina. The amount of light entering the eye is controlled by the Iris. Sharp focusing is achieved by altering the shape of the lens. The shape of the lens is controlled by the ring of ciliary muscle which runs round the outside of the lens. (http://www.riverdeep.net/current/2002/01/012002_images/eye.jpg) Defects in the eye:- . Long Sight (Hypermetropia) In this condition we can see distant objects more clearly that ones that are nearby. This is usually because the cornea is not curved enough, which reduces the angle of refraction, and the lens cannot accommodate sufficiently to bring the diverging rays from near objects into sharp focus on the retina. 2. Short Sight (Myopia) In this condition near objects are clearly seen, but distant objects cannot be brought into the focus. It happens when the cornea is too curved; the light from distant objects is refracted too much and comes to a focus in
