Equipment/Diagram
Ammeter,
Voltometer,
Leads,
Crocodile Clips,
Nichrome wire,
2v Battery,
Ruler,
Scissors,
Method
I will be carrying out my experiment in 5 stages, (10cm, 15cm, 20cm, 25cm, 30cm). But first of all I shall be gathering my equipment listed above and begin to measure out my first length of nichrome wire, which is 8cm. Then I’ll clip the wire safely to the croc clips as close to the edge as possible. I shall then switch the battery on at 2v, and 2v only. Once both the voltmeter and ammeter reach there peek both results will be recorded. I will then switch the battery off and arrange the equipment for the next length of wire.
Once all results are recorded for each length and the resistance is calculated, I will then perform the experiment two more times for accuracy, followed by working out a mean average.
When undertaking the experiment I will have to make sure that each length is cut exact to its requirement and that I record all volts and amps accurately.
(This is the formula I shall be using to work out my resistance)
Where R= resistance, I=Current and V=Volts
R = V
I
Results Tables
Experiment 1
Experiment 2
Experiment 3
Graph
Conclusion
I think that from my results I can safely say that my prediction was right. The resistance did change in proportion to the length. This is because as the length of the wire increased the electrons that made up the current had to travel through more of the fixed particles in the wire causing more collisions and therefore a higher resistance. We can now work out what the resistivity of the wire should be from our results using a formula.
Evaluation
I feel that overall my results were quite accurate. This is can be seen when we look at the graph, which shows a straight line with all of the points apart from one being very close to or on that line. I didn’t really have any anomaly points in my graph so therefore the straight line was very truthful.
My experiment did have a few points that may have effected the over results. Firstly the temperature of the wire was not necessarily 20C when we preformed the experiment and the material of wire may not be as pure as it should have been, impurities were probably added every time it was passed around different hands). The main reason for this was probably due to the equipment that we used being inaccurate. This did not stop us from seeing the trend, though, because the equipment would have been out by a constant amount each time therefore there was a constant error. So the trends that were predicted in the plan were still shown.
Most of my mistakes would probably have come from the cutting of the wire, this would have been due to the fact that trying to hold a pieces of bent wire next to a ruler and trying to snip at the same time proved very difficult. Also trying to attach the crocodile clips on at each end was a bit of a task.
I do not think that doing any more results in our experiment would have made it any more accurate. I feel that the only way to make it more accurate would be to use a different method
