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How the length of wire affects its resistance.

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Introduction

How the length of wire affects its resistance

By, Harinder Khaira

Introduction-

In our investigation we are trying to find out that what are the factors which effect the resistance of a resistance wire. Through textbooks and information from the Internet I have identified these factors.

-The length of the wire

-The thickness of the wire

-The material of the wire

-The temperature of the wire

Through my general knowledge and reading through various textbooks I know that electrons move more easily through some conductors than others. And that the resistance is the opposing force, which slows down the flow of electrons. And through learning I know that good conductors have low resistance and poor conductors have high resistance. And a resistance is caused in a circuit when a free moving electron collides with an ion where the kinetic energy of the electron is transformed to heat energy and therefore it loses its speed and in turn the material the electrons were flowing through gets hot. From past learning I know that the free moving electron is said to be “free” because they have enough energy to escape from the attraction of the nucleus, and move with a random motion. And they will flow in one direction from the negative side to the positive of the circuit (because the electron is negatively charged) when I pass a current through the circuit.

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Middle

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                                                                                              Voltmeterimage13.png

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                                                    Ammeter                    

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                                                                                                                                             100 cmimage19.pngimage18.png

                                                                                                                                              Ruler

                                                                                      Test wire

In this investigation a simple circuit will be set up to read the voltage and current when the length of the wire changes. The circuit should be set up as above. The length will range from 10cm - 100cm (1m) with intervals of 10cm. Moving the crocodile clip across the wire on a ruler will change the length of the wire. If I am doing the experiment rite then I should be able to spot a pattern straight away. This way I would be able to see if the experiment is going ok. Of the pattern does not show up then the experiment that is being carried out is wrong. The wire that I will be using should be the same one through out the whole experiment. That is why it was a good idea to do a preliminary to see the maximum electricity that the wire can take before it starts to melt. If the wire melts or burns then the whole experiment will have to be started again.

Fair testing-

To make this experiment a fair test I have to make sure I keep the other factors, which affect its resistance, constant throughout the experiment by keeping the wire and its width the same. And to test the wire at room temperature.

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Conclusion

Evaluation-

Generally I am pleased with my results as they formed a straight line on the graph, though some of the points were not in favour of the line. However I can explain this, when the electrons and ions collide with each other heat is produced and to this result the metal wire gets hot and temperature is one of the main factors which effect the resistance of the resistance wire. Because this would give the electrons more energy so it could collide with more ions in one go. That is why my results may not have been very accurate. Another possible reason could be due to the fluctuation of the pointer on the ammeter and so I had to catch the reading very quickly. And again due to this I may not have got very accurate results. Overall I’m very confident with my results and I believe I have made a sensible conclusion that the resistance is directly proportional to the length with my results even though I made slight errors the conclusion agreed with my prediction.

The possible improvements that I could have made with my results could have been to use digital meters or to use an ammeter that did not fluctuate and could have used another resistor to make sure that the right amount of current went through the circuit. I could have also used an ammeter and a voltmeter that would allow me to have a wider range of readings so I could test the resistance of the wire in 5cm length so I could explain my conclusion in more detail.

...read more.

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