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 in resistance in wires
Investigating Resistance in Wires Aim In this investigation I will be looking into the theory of resistance and current in wires; this theory is called Ohms Law. By doing the experiments I will be hoping to prove Ohms law correct, and testing to see if it remains constant as the voltage, and wire lengths vary. Related Theory Resistance is measured in ohms (), resistance can be calculated by using the formula V = I × R V = voltage measured in volts (V) I = current measured in amps (A) R = resistance measured in ohms () This is the formula called Ohms Law. Ohms law is the relationship between voltage, current and resistance. For a metal conductor at a constant temperature the current is directly proportional to the voltage. This means that if the current increases the voltage will also increase in the same proportion. For example: If a cell provides a voltage of 1 volt and the circuit has a resistor of 1 ohm connected to it an ammeter would read 1 amp. If the cell was replaced with a 2 Volt cell the ammeter would read 2 Amps. Resistance is caused by electrons bumping into ions. If the length of the wire is doubled, the electrons bump into twice as many ions so there will be twice as much resistance. If the cross-sectional area of the wire doubles there will be twice as many ions and twice as many electrons bumping into them, but also twice as many electrons getting
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 *
How does the power dissipated by a light bulb vary with voltage?
How does the power dissipated by a light bulb vary with voltage? Plan Introduction For my experiment, I am going to investigate how the power dissipated by a light bulb varies with voltage. To find this out, I will need to do an experiment to test this out and repeat it another two times. Meaning of terms Current - Current is the flow of electric charge. An ammeter measures current in a circuit. Voltage - Voltage is the potential difference between two points in a circuit is the electrical energy gained or lost by 1 coulomb of charge. A voltmeter measures voltage between two points in a circuit. Resistance - If a component has resistance, it changes some of the electrical energy passing through it into another form of energy. A rheostat can increase or decrease its own resistance so in that way I can control the amount of voltage across the light bulb whilst doing the experiment. Prediction I think that as the voltage across a light bulb increases, the power dissipated by the light bulb also increases but at a greater rate. This is because as the voltage increases, the current also increases. This is because if the current is the amount of electrons flowing through a circuit at any point in a circuit and if the voltage increases then the current must increase as the electrons flowing through that point are flowing faster. Therefore, as the voltage increases, the
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
Investigating factors that affect the bounce height of a squash ball
SC1 Investigation 6/10/06 Investigating factors that affect the bounce height of a squash ball Christopher Lewis Candidate number: 2670 SC1 Investigation Investigating factors that affect the bounce height of a squash ball . Planning ) Investigating factors that affect the bounce height of a squash ball. 2) Background Information I have decided to investigate how the height from which a squash ball is dropped affects the height of its bounce. When a ball is dropped, it accelerates until it collides with the surface - an impact. It then recoils, and some of the energy is reflected back upwards, causing it to bounce. I believe that as the height from which the ball is dropped changes, the speed of the ball at the moment of impact will also change. This is because when the ball is dropped, it accelerates due to the force of gravity. Newton's law states that if the force acting on an object is not zero or the resultant force acting is not zero then the object will accelerate. In this case, the force acting on the object (gravity) is greater than the air resistance, so the object accelerates downwards. Theoretically, when the ball is travelling at a faster speed, there will be more force at the point of impact (due to the increased kinetic energy). Therefore, more potential energy will be stored in the ball as the collisions takes place, which will then be converted
