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Factors that affect the resistance of a wire

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Introduction

Peter Vaughan 11SEscience coursework

Coursework:

Factors that affect the resistance of a wire

Aim

        In my coursework I will be investigating the factors that affect the resistance of a wire. Theses factors are temperature, length, thickness and the density of a wire. I will be using length, as it is easier to use than the other factors

Science Theory

         The theory of this experiment is Ohm’s law, which states, “The current and voltage will be directly proportional as long as the temperature remains constant.” Ohm’s law is correct at varying temperatures as the resistance will vary as well.

        In this experiment positive ions and negative electrons colliding cause the resistance, this subject leads us on to the next, this is the structure of a metal. This diagram shows three of the factors in there simplest form.

Length

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        e-         e-                                         e-           e-            e-          e-image02.pngimage02.pngimage02.pngimage02.pngimage07.pngimage07.pngimage02.pngimage07.pngimage07.pngimage00.pngimage05.pngimage01.pngimage07.png

        This diagram shows that in theory the longer the wires the more resistance there will be.

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Middle

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        This diagram shows that the thicker the wire the less resistance there will be as there is more space for the positive ions and the negative electrons do not collide. This means the thinner the wire the more resistance and there will be more collisions between the positive ions and the electrons.

Type of wire (Density)

Low-densityHigh density

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                               The thickness and lengthimage06.pngimage05.pngimage06.pngimage05.png

                                          Remain the same.image05.pngimage05.pngimage05.pngimage05.pngimage06.pngimage06.pngimage06.pngimage06.pngimage05.pngimage06.pngimage06.pngimage05.png

            If you increase the density there will be more resistance, as there are so many ions and electrons in such a confined space. All of theses collisions produce heat.

Here are the Ohm’s law graphs, which show this theory at a constant and non-constant temperature:

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Prediction

        We know that increasing the length of the wire will increase the resistance; so if we might double the length will it double the resistance? My prediction is that if I double the length of wire I will not double the resistance.

Fair test

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Conclusion

Evaluation

I believe that my experiment went well and the procedure was suitable to make a valid conclusion based on the evidence I obtained. My results were not anomalous and enabled me to draw a good line of best fit on my graph, but there are improvements I could have made to my experiment such as checking the consistency of the gauge of the wire throughout its length and using a digital ammeter during the experiment to gain even more accurate readings.  Overall I think that my experiment was a success and that my conclusion was supported by my prediction.

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This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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