954 words - 4 pages

Resistance in a wirePlanning -The resistance of a wire can be affected by certain factors:Length of wireCross sectional arearesistivity (type of metal)Type of wireTemperatureI chose to investigate how length affects the resistance in a wire. This means that the other factors (variables) must be controlled. This means I must keep the same type of wire, the same material of wire (a preliminary experiment will help determine this), and the same cross sectional area and maintain a constant temperature of the wire as any increase in temperature increases resistance. These factors must me kept controlled to ensure a fair test.Preliminary ExperimentI conducted a preliminary experiment to determine ...view middle of the document...

This transfer on collision is what causes resistance. So, if we double the length of a wire, the number of atoms in the wire doubles. This increases the number of collisions and energy transferred twice, so twice the amount of energy is required. This means the resistance is doubled.PredictionI predict that that length of the wire will be directly proportional to its resistance. When the length is increased by e.g. Double, I think that the resistance will also double. This relates back to the theory that if you double the length of the wire, the number of electron 'jumps´ and so energy required doubles as well. The electrons will have double the distance to travel so the resistance will double.MethodA length of wire is taped at both ends to a metre rule. It is then attached to a circuit like this one with crocodile clips.One of the crocodile clips is then moved around the metre rule from 100cm, to 80, to 60 to 40 to 20. I will then take 6 readings from the voltmeter and the ammeter at each length. This will give a range of readings to determine resistance using the formula R=V/I. The readings will be plotted on a graph, and then the gradient of the graph will be measured to get the resistance for each length of wire.ResultsAnalysisThe graph was is a straight line through the origin, which means resistance is directly proportional to length. This means that if the length is 20cm, and resistance is 1 Ohm, then if...

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