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Physics Resistance Investigation Aim: Does the length of wire affect resistance? Introduction There are many factors that are known to affect the resistance of an object. It is determined by the sort of the substance which is composed used. The dimensions of the object and the temperature also effect the materials resistance. Also the structure of metals. Density too, has a large affect on the amount of resistance. The resistance depends upon the amount of denseness e.g. a large surface area has less resistance because a small area has tightly packed atoms which in turn rebound many of these electrons. The factors that can be investigated in Physics are those known as quantitative results – these are results that have continuos data (such as length). The Factor that I will be investigating will be the length of wire. I am not investigating temperature as it is too difficult to measure the temperature within a wire. Temperature effects the wire but as I am using the same piece of wire, in the same classroom and on the same day, I think that the wires temperature will be fairly equal in all my experiments. Though it will not be 100% accurate. Background Knowledge The knowledge that I already have is on Ohms law, also how to measure resistance using a voltmeter and an ammeter. Ohm's law states that the amount of current flowing in a circuit made up of pure resistances is directly proportional to the electromotive force impressed on the circuit and inversely proportional to the total resistance of the circuit. I can now work out the resistance using the current and Voltage: R=V/I R - resistance in ohms (W ohms) V - voltage (volts) I - current (amperes) Prediction In this experiment I predict that the longer the piece of wire, the greater the resistance will be. This is due to the idea of the free moving electrons being resisted by the atoms in the wire. In a longer piece of wire, there would be more atoms for the electrons to collide with and so the resistance would be greater. The relationship between the wire length and the resistance should be directly proportional. This is because in a wire twice the length of another wire there would be double the amount of atoms causing the resistance. An example of this would be in a 20cm wire. The electrons would have to travel double to distance if it have to go through a 10cm wire. This would in turn double the amount of atoms that the electrons would collide with and then resistance would double. What Is Resistance? The Rate at which the electricity is flowing is called the current in an electrical system (how fast are the electrons moving).
Approximate Word count = 1795
Approximate Pages = 7.2
(250 words per page double spaced)
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