I predict that the longer the length, the larger the resistance. I think this because electrons will have a longer distance to travel and so more collisions will occur. Due to this
the length increase should be proportional to the resistance increase.
To make sure that my experiment is safe I have decided on safety issues that are important. I will handle the power supply carefully. I am going to only use a voltage of 6 volts and keep this constant. I will be careful when handling live wires.
To make sure my experiment is a fair one I will keep the voltage the same throughout (6V). I will use the same reel of wire and it will be the same diameter throughout (26SWG).
Apparatus
This is a list of the apparatus that I will use.
- Nichrome Wire (26SWG)
- Leads
- 6V Cell
- Amp Meter
- Volt Meter
- Crocodile Clips
- Metre Rules
This is a diagram of my circuit.
Method
First I will set up my circuit as shown in the diagram. We will then connect the crocodile clip at the first point that we are recording at which is 0.5m. We will then repeat this process at 1m, 1.5m, 2m, 2.5m, 3m, 4m, 4.5m and 5m. After our 1st set of readings is complete we will repeat this process for our 2nd and 3rd readings so we have a good set of results to work from. We will use Nichrome 26 SWG throughout this experiment.
Results
We have taken 3 sets of readings so I have 3 tables and an average table.
Table 1
Table 2
Table 3
Average Table
I have decided to plot my results on a graph. I have chose to use the average of my 3 readings to plot on my graph, as this will give the overall trend of my readings.
Conclusion
I have found out that if the length of a piece of wire increases then so does the resistance. From my graph I have shown that my prediction was correct, as the Line of Best Fit is a straight line proving that the resistance of the wire is proportional to the length of the wire.
The length of the wire affects the resistance of the wire because the number of atoms in the wire increases or decreases as the length of the wire increases or decreases in proportion.
The resistance of a wire depends on the number of collisions the electrons have with the atoms of the material, so if there is a larger number of atoms there will be a larger number of collisions, which will increase the resistance of the wire. If a length of a wire contains a certain number of atoms when that length is increased the number of atoms will also increase.
Evaluation
From looking back at my results I think they are reliable as they have followed the trend that I expected. Because of this I feel that I have done my investigation very well as I have obtained the results that I was expecting to get.
If I were to repeat the experiment again I would use less voltage than 6V. I would use 2V because this would eliminate any chance of the wire burning as in this experiment the wire did get quite hot at the ends. The next modification I would make would be to 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.
