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GCSE: Electricity and Magnetism
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Prediction: For length of wire, I predict that the longer the wire the bigger the resistance. Scientific Knowledge: The resistance of a longer piece of wire is greater than that of a shorter wire. This is because the electrons have further to travel in a longer piece and this means they are more likely to collide with the positive ions, therefore if the electrons collide with the ion they will be slowed down considerably because they will have lost some of there energy as some of it's energy has been transferred to the ion in the collision.
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Also, a piece of wire with a cross-sectional area of 1mm� would have twice the resistance of one with a cross-sectional area of 2mm�. Plan Safety In this investigation I will be using electricity to I will make sure all surfaces involved are dry as will all relevant pieces of equipment. Also, the wire may accumulate some heat so I will not touch it during the experiment. Preliminary experiment In this experiment I will use the circuit shown on the next page. I will try several different of wire and several voltages to see which are viable for accurate measurements.
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I am assuming that the temperature will not change during my investigating. Method Equipment needed: 1 x Power Pack (to give varied voltage) 1 x Voltmeter 1 x Ammeter 5 x wires (with crocodile clips) wire of varied length Controlled variables: Temperature (room temperature) Wire material Dependent variable: Resistance Independent variables: Thickness of wire Length of wire Circuit diagram First, set up the experiment as shown above. Turn on the power and set the power pack so that the voltmeter reads 0.1 volts. Take the reading from the ammeter recording both the current and the voltage.
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When measuring the length I will always use the same material: Constantan wire. Also I will make sure that the wire does not get hot by not measuring any less than 10cm. Also, I will always use the same thickness wire, 32SWG (standard gauge). However, when I am looking at the factor of thickness I will make sure that the wire does not get hot, that the wire is Constantan wire and that the wire is always a set length, 50cm long.
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Nichrome The reason why Nichrome does not allow current to pass throw is because nichrome hold the electron very hard and makes it more difficult for the current to flow through the mental, also gives lots of energy is released. . Copper The reason why copper allow current to pass throw is because copper does not hold the electron very hard as nichrome and constantan and so is allows more current, and also releases energy. Also I predict Copper allows more current because copper does not hold on to their electrons very hard as nichrome and constantan, which eventually allows more current to pass through, and also releases energy.
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Firstly I will attach a piece of wire to a ruler stick and pull it as tight as possible. I will then set up a circuit consisting of a power pack, voltage measure, amplitude measure and a variable resistor. I will then connect the circuit through the wire on the ruler stick, recording the results at each ten centimetre interval until I reach ninety centimetres. When doing the experiment I will keep the voltage on the power pack below six volts, avoid touching the wire as it gets hot and be careful not to cut myself on the sharp edges of the wire.
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In 1911, Onnes began to investigate the electrical properties of metals in extremely cold temperatures. Onnes as well as many scientists had known for many years that the resistance of metals fell when cooled, but it was not known what limiting value the resistance would approach, if the temperature were reduced to very close to 0 K. William Kelvin, along with many other scientists believed that electrons flowing through a conductor would come to a complete halt as the temperature approached absolute zero.
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Any conductor possessing resistance gives off heat when a current flows through it. Joule's law describes this effect. Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire. Ohm's law: The current flowing through a metal is proportional to the potential difference across it, provided that the temperature remains constant. We are going to use metals, which obey ohm's law, metals which give us a constant value for resistance (gradient).
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EIN This can be shown in another way, showing the breaking down of the bonds: E = Energy H = Hydrogen O = Oxygen C = Carbon This proves that more energy will be given off when more bonds are formed. Set Variable Each time I do the experiment, I will change the alcohol. The different alcohols I will use each time are Methanol, Ethanol, Butanol, and Pentanol. Measured Variable Each experiment, I will measure the difference in weight of the alcohol before and after the experiment, to calculate the energy given off.
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Also we need to keep the voltage relatively the same which may not be possible with thickness, as a voltage which may cause the thin wire to smoulder may not even cause a current readable when passed through the thick wire. Material Different materials have different levels of resistance. Wires that have a greater number of ions in a set space will be more resistant. This is not a very good variable as there only three types of wire that can be used which is not a big enough range.
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Also the ball is made from rubber, and rubber is very flexible so it will deform for a fraction of a second. As it is a solid, it will return to its original shape when the atoms return to their original shape. The ball gains its most gravitational potential energy, when it is held at the set height. This turns to kinetic energy when the ball hits the chosen surface. This will occur until the energy is fully distributed by either kinetic or gravitational potential energy.
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This can also be shown in a graph, where it goes through origin, showing that they are directly proportional. Also, we can use the equation Y=Gradient This also shows us how current and voltage is directly proportional. Prediction I predict that as the length of the wire increases so will the resistance. I also predict that the length of the wire will be directly proportional to the resistance. Metals, (such as the Nichrome wire that we are using) contain a sea of free electrons, which are negatively charged and flow throughout the metal. The resistance of a conductor depends on two things 1 Its dimensions.
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I will have to switch on and off the power supply quickly because short lengths of wire got hot quite quickly that is why I will start of at 30 cm, because the preliminary experiments showed that very short pieces of wire get hot very quickly and they go red, which can be a danger in case it will start up a fire. To collect my results I will draw a table, which will show the voltage and the current measurements, and also the resistance, which can be worked out by using this formula: Resistance = volts/ampere I predict that they longer the wire the higher will be the resistance.
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This impedes electron movement. The higher the temperature the higher the resistance in the wire. How the length of the wire affects resistance Increasing the length is like increasing the number of resistors in series as each part of the wire has its own resistance. The longer the wire is the less the potential gradient. As the potential difference is directly proportional to the current flowing through the circuit, the current is also reduced. This means that the resistance of the wire is higher.
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To measure the potential difference across a component a voltmeter is used. A voltmeter is connected across a component. The idea is to measure the amount of energy passing the point before the component and then the amount of energy passing the point after the component. This allows the voltmeter to calculate the amount of energy being used by the component through simple subtraction. A voltmeter can only be connected in a circuit across a component because it is designed to measure the amount of energy being used up and components are the only parts of circuits in which energy is used up.
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The property that converts electrical energy into heat, in opposing electrical current, is resistance. The electrical resistance of a wire can be defined as the ratio of the voltage applied to the electrical current at a constant temperature that flows through the wire. Ohm's Law states that: V = IR Where: V is the voltage I is the current R is the resistance of the conductor This formula can be rearranged so that Resistance becomes the subject: R=V/I This means that the resistance of a wire conductor will remain constant provided that the temperature also remains constant.
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V = I x R Where I = Current (amps) V = voltage (V) R = Resistance (?) This equation can be used to determine the electric current of the circuit and light bulb, given the voltage and resistance. Equipment * 4 x AA Switched Battery Enclosure * Multimeter * 3 x Torch Bulb * 4 x AA 1.5V Battery * Bakelite Bulb Holder * Wires Method Series Circuit 1. As shown in the diagram below, connect the wire to the bakelite bulb holder, while making sure that the bulb is screwed on. Macintosh HD:Users:TrixSwift:Desktop:Screen Shot 2013-10-20 at 6.20.18 PM.png 1. Using the multimeter measure the resistance of each bulb.
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Length ? When increasing the length of the wire, it increases the length of the path that the moving charges have to pass, so the charges are likely to face collisions with other atoms that are not moving. 4. Temperature of the wire ? Once increasing the temperature of the wire, it increases the resistance because the atoms of the wire gain more energy as it heats up. When the atoms heat up, they vibrate faster, causing more collisions, which then increase the amount of resistance.
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It is this repulsive force that drives the train forward. 1. Electromagnetism ? The magnets used are no ordinary magnets ? they are electromagnets. A solenoid is made using wires and an aluminium core. When current flows through the wires the magnet is magnetised. The speed of the train can be controlled by the amount of current being supplied to the electromagnets. How is magnetic levitation achieved? There are two ways to levitate the train ? 1.
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We will also keep the temperature the same however again the temperatures will he harder to control. For working out resistance due to temperature the factors the will affect the resistance are the temperature, the thickness of wire and the length of the wire. To keep this a fair test we will only change the temperature, we will keep the length and thickness the same as these both affect the resistance. A factor that affects all of this is what type of wire we use, as Nicrome has a much greater resistance than silver.
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Aim: I am going to carry out an investigation to find how the resistance of Resistor 1 affects the output voltage of a potential divider circuit
They can be used to split the voltage of a circuit) to find out how changing the resistance of Resistor 1 affects the total output voltage of a potential divider circuit. I will take all possible variables into consideration and I will try to make this experiment one which will create reliable and as accurate results. The experiment will be carried out in the school science lab where I will record the results and then conclude my experiment to prove whether my hypothesis correct or false.
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In the cooling tower, steam is cooled in a condenser. Then it's sprayed into the giant cooling towers. Most of the water condenses on the walls of the towers and drips/falls back down again. Only a small amount of the water used, escapes as steam from the towers, but large amounts of heat and energy are lost. The turbine is linked to a generator, so the generator spins. As it spins, the generator uses the kinetic energy from the turbine to make electricity. This electricity travels out of the generator to a step up transformer. Electricity loses some of its energy as it travels down wire cables, but high-voltage electricity loses less energy than low-voltage electricity.
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The first electricity generating wind turbine, was a battery charging machine installed in July 1887 by James Blyth to light his holiday home. Only 30mwh of energy is being produces from renewable energy resources and another 1000mwh are needed to meet the target. The government say that 200mwh of that will come from off shore wind turbines, and the other 800mwh will come from on shore wind turbines, doing this will cost them £700million. A Wales energy group say that the assembly government are pursuing the wrong technology to meet its target.
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Also, like poles repel and unlike poles attract. Picture taken from: http://www.swe.org/iac/images/NewMagnet.jpg (to show Like poles repel, unlime poles attract) Secondly, induced magnetism is the phenomenon whereby a magnetic substance is magnetized by a magnetic field. Thus when magnetized, it always results in 2 poles and leads to attraction. Thus it is very important as the theory of magnetism is needed to understand how magnets work. http://www.electronics-tutorials.ws/electromagnetism/mag3.gif http://cdn4.explainthatstuff.com/magneticdomaintheory.png Arrows represent magnetic domain In magnetic substances, atoms behave like tiny atomic magnets. With a group of atomic magnets pointing in the same direction, all domains are aligned in the same direction.
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