Fair Test: To make this test fair we will make sure that none of the variables change apart from the length of the wire. This is to make sure that my results give an accurate indication of whether or not my prediction is true. I will also make sure that the temperature of the wire stays the same for each experiment. To do this we will allow the wire to cool between investigations. This is important as it could make the results inaccurate. Keeping this investigation fair is very important as if I we find there is a fault making it unfair then the entire investigation will have to be repeated.
Preliminary Results:
I chose the think nichrome wire as it had the best range of resistance. However this could be altered if I had collected another result for thick nichrome and thick copper. As I had collected only one result for them and two sets of results for the others. This therefore makes my results slightly unfair. Although I do not think it would have altered my choice.
Method:
- Plan investigation
Build the circuit according to the diagram
Cut the wire to 70cm and place it in the end
Test the wire and record the resistance
Let the wire cool
Test it again
Repeat but cut the wire down the wire by 10cm each time.
Safety
To make my investigation safe we will
- Not touch the wire when the current is running through it as you could get an electric shock and because the electricity is running through it heat is produced as a waste product and therefore you could get burnt.
- Do not allow the wire to get wet, as it will affect my results.
Put the wire on a heatproof mat whilst conducting the experiment as it could melt onto the table and get stuck.
Results
I will not take average results, as the anomalous result will throw the average.
Conclusion: I conclude that the longer the wire, the more resistance there is.
Here the wire is shorter and there are few obstacles in the way for the electrons to pass through.
Here the wire is longer and as you can see there are far more obstacles for the electrons to pass through. There is double the amount of collisions so therefore there is double the double the resistance.
Looking at my first set of results it is clear to see I have an anomalous result. Many things could have caused this, for example, there could have been a fault with the ammeter/voltmeter, we could have cut the wire to the wrong length, or it simply could have been how the results were meant to turn out. My first set of results seemed to follow a trend so it is these I will create my graph with.
Evaluation
I think that the longer the wire the more resistance there is. This experiment went rather well however it could have been improved. To improve the experiment I could take more readings from different lengths and also take more than two readings form each length to find a better average. By doing this I may not have come across my anomalous result.
If the wire was to be at an extreme length I think that my results would have eventually trailed off. This is because resistance can only get so high, however to find out this I would need to further my investigation.
