Реферат: Does The Resistance Rate Depend On How
Название: Does The Resistance Rate Depend On How Раздел: Топики по английскому языку Тип: реферат |
Much Constantan Wire Is In The Circuit? Essay, Research Paper Aim The aim of this experiment is to investigate or find out how the resistance of a wire is affected by different lengths. How the length of a constantan wire affects its resistance. Prediction Constantan is a malleable alloy of nominally 60% copper and 40% nickel. I should expect to see the resistance level rise, as the length of the constantan wire gets longer. I think this because the more wire there is for the electricity to pass through the more ions it has to pass. I expect to see a fixed relationship between the four variables. Apparatus · Ammeter · Voltmeter · Power Pack · 2 Crocodile clips · Wire cutter · Constantan wire · Meter rulerMethod · Cut out 10 pieces of constantan wire measuring 10cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm, and 100cm. · Set up the equipment using the diagram · Place the constantan wire between the two crocodile clips · Turn on the mains · Read out and record the first reading the ammeter and volt meter gives · Repeat this for all the lengths of wire taking three sets of readings for each length.Variables · Length of wire · Voltage · Current Diagram ? Safety Issues We carried out the experiment with great caution. No protective equipment was necessary. The power pack reduced the mains voltage to a safe level for working. We kept the working area tidy and dry, to avoid short circuiting. Results and graph. (See separate sheets attached.) The experiment was carried out on two separate days the first three readings were taken on the first day and the remainder on the second with a different set of apparatus. This may explain the anomalous step in the graph between the reading taken at 3 and 4 centimeters. From the results table it can be seen that some inconsistent readings were obtained from both the voltmeter and the ammeter, this was maybe because there was a fault in the equipment or possibly a poor connection. However when calculating the average of the three readings the ones that were obviously wrong were ignored.Conclusion On each day a clear trend was established, the resistance increased in direct proportion to the length of wire. I would expect the resistance to be zero for zero length of wire. The formula for a straight line is y=mx+c where ?m? is the gradient and ?c? is the intercept. With ?c? equal to zero the formula becomes y=mx or in this case r=ml. In this particular case however the accuracy of the results is not sufficient to prove this absolutely. To make this a more accurate experiment I would use equipment that showed no inconsistent readings. ?? Sources of information: www.ohmslaw.com 3a3 |