However I cannot stop the wire getting hot as it is out of my control because the ions and electrons have to collide in order for me to test and in return heat energy is produced making the metal wire hot, which may affect its resistance. However I can try to minimise this error by turning the circuit off as soon as I get the reading. So that there would be less collisions as possible between the electrons and ions I could also make this a fair test by taking each reading three times then take the average to calculate the resistance.
So that the numbers I get after each calculation would be fair as possible and sensible to my conclusion. The power pack will first be Preliminary- The problems that I saw in the preliminary investigation were as follows; voltage on power use, eliminating links on to the wire, using a rheostat to get precise readings on the ammeter and the voltmeter. Table of results- Length V-voltage I- current R1- v/I V-voltage I- current R2- v/I V-voltage I- current R3- v/I Average 1Conclusion.
The graph gives a reasonable straight line and it shows a positive correlation between the length of the wire and its resistance. And the second graph clearly shows that an increase in the length of wire results in an increase in the resistance, which tells us that the resistance is directly proportional to the length Just as I predicted this could be explained to the fact the free moving electrons colliding with the ions in the metal wire cause that resistance.
And the longer the wire the more collisions there will be. And due to this we can say that R=KL Which means that the resistance stays constant to the length 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 Im 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.