Secondly, the width of the wire is a factor. This will cause resistance to decrease because of the increase in space in the wire. The increase in space means that there is more space for the electrons to flow freely because there would be fewer collisions with atoms.
Thirdly, the material used would be a factor. If the material being used contains atoms with a large number of electrons on the outer shells, then this means there are more electrons available. So, in theory, if the material has a large number of atoms, there should be less resistance, because of the higher number of electrons .If the atoms in the wire are closely packed, then this will cause an increase in resistance, due to frequent collisions. To do this I would use the same length and width of many different wire materials, using the same amount of voltage each time.
Finally, the length of the wire is a factor. The longer the wire, the longer it will take electrons to get to the end of the wire. This is because there will be more collisions between electrons and atoms. So, in theory, the length of the wire should be directly proportional to the resistance.
Due to the effectiveness of this method, I have decided to use the length of the wire as the factor that I am going to use.
Prediction:
I predict that, the longer the wire is, the more resistance there will be due to more collisions between the electrons and atoms. The length of the wire should be approximately proportionally the same as the resistance. In theory, if the wire is doubled, then so will the resistance. If the length is twice as much, then there will be twice as much collisions, which would increase the resistance.
Method:
Apparatus:
· Crocodile clips
· Ammeter
· Voltmeter
· Power supply
· Meter ruler
· Connecting wires
· Sticky tape
· Thin wire
The resistance is going to be recorded at nine different lengths. I have chosen to record the results at this amount of lengths, as it will give me a much more accurate result at the end of the experiment.
The way to calculate the Resistance relies on this formula:
Resistance = Voltage/current
I will use the Voltmeter provided to get the voltage, and the ammeter provided to get the current (in amps).
Results:
Here are result tables from my main experiment:
20 cm:
30 cm:
40 cm:
50 cm:
60 cm:
70 cm:
80 cm:
90 cm:
100 cm:
Average resistance:
Conclusion:
In conclusion, I have found that my prediction was correct. I said that the resistance would increase approximately proportionally to the length, this was correct. It proves the fact that the longer the wire is the more collisions there are between atoms and electrons. So if the wire increases in length, so does the resistance. If the wire decreases in length, so does the resistance.
Evaluation:
This experiment has gone satisfactory, but there have been certain things in the experiment that I have not been pleased with.
Some of my results have turned out anomalous. This mainly being:
60cm Anomalous
I have probably ended up with this anomalous result because of an error in recording my results.
I have noticed, now that I have finished my coursework, that there are a number of things I could have done to get more accurate results:
Firstly, I would do the experiment using the width and the material used as a factor too, just to make sure that my averages are as correct as possible.
The next thing I would have done is to use pointers instead of the crocodile clips, which I used. This is because pointers are a lot more accurate, because they have a smaller surface area on their tips than crocodile clips. This in effect would give much more accurate measurements.
