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What affects the current through a wire?

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Introduction

What affects the current through a wire?

Planning

Variables

1. Temperature: If the wire is heated up the atoms in the wire will start to vibrate because of their increase in energy. This causes more collisions between the electrons and the atoms as the atoms are moving into the path of the electrons. This increase in collisions means that there will be an increase in resistance, slowing the current down.

2. Material: The type of material will affect the amount of free electrons that are able to flow through the wire. The number of electrons depends on the amount of electrons in the outer energy shell of the atoms, so if there are more free electrons in the atoms then there must be more electrons available. If the material has a higher number of free electrons then the material has a lower resistance. Conversely if there are less free electrons then the resistance of the material is said to be higher.
3. Wire length: If the length of the wire is increased then the resistance will also increase as the electrons will have a longer distance to travel and so more collisions will occur. Due to this
the length increase is directly proportional to the increase in resistance.
4. Wire diameter: If the wires diameter is increased the resistance will decrease.

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Middle

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Table of results

Length (cm)

Current 1 (amps)

Current 2 (amps)

Current 3 (amps)

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Conclusion

·        Imperfections in the circuit. Any basic faults in the circuit such as a faulty wire could have caused a change in results.

·        Accuracy on Length. The only available method for measuring was by ruler and hand. It would be impossible to get an accurate length using this technique. It was measured to the best ability but the margin of error could have been up to 1cm bearing in mind the poor method in which the conductor was held in position; ‘crocodile clips’. A more accurate method of measuring the wire is necessary, as well as a more effective method of connecting the conductor. If I were to do it again I’d use pointers instead of crocodile clips, I would do this because pointers would be more accurate. The pointers would be more accurate because the tips have a much smaller area than the crocodile clips giving a more accurate measurement of the length of wire.
As well as making these modifications I would also improve my Investigation by testing the same wire but different widths of that wire. I would do this to expand on my Investigation. I could also do test different materials.

Besides these minor flaws, the experiment was very reliable and efficient. It was a perfect method of calculating resistance. After looking at the basic out come of the experiment you could say this investigation was a complete success.

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