To do this I would use the same length and width of many different wire materials, using the same amount of voltage each time.
The length of the wire is a factor. The longer the wire, the more atoms there will be to collide with. This is because there will be more collisions between electrons and atoms. So, the length of the wire should be directly proportional to the resistance.
This would be very easy to do, and give accurate results. Because of the length being proportional to the resistance, I could link the length of a wire with the resistance of the wire.
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 collision, which would increase the resistance.
Method
Apparatus
· Crocodile clips
· Ammeter
· Voltmeter
· Power supply
· Meter ruler
· Connecting wires
I set up my experiment using the equipment shown above.
I started the experiment by using crocodile clips and clipping the Wire (over 1 meter long) to the meter ruler. Then the power supply was switched on which was connected to the wire via the crocodile clips. The resistance was then recorded down for various lengths ranging from 20cm to 100cm. I then plotted these results on a graph.
To collect the data for my graph I had chosen to take a range of 9 lengths. I had chosen a range of 9 as to plot an accurate graph I will need at least 9 points to mark on the graph. The lengths that I had chosen were as follows: 20cm, 30cm, 40 cm, 50cm, 60cm, 70cm, 80cm, 90cm, and 100cm. I have chosen these lengths because they are easily measured by the meter ruler and give a good range of results.
I will repeat my results twice
1st experiment Results
2nd experiment Results
Average Results
Analysis
I think that my experiment went quite well because all my graphs had straight lines showing a strong relationship between the length and the resistance.
But I could have improved this method in a couple of ways. For example I should have used pointers instead of crocodile clips because they are far more accurate, this is because they have a far smaller tip than crocodile clips and they would give a more accurate measurement of the wire. Also pointers would not have compressed the wire like crocodile clips. Crocodile clips have a spring in them to keep them shut and this could have compressed the wire therefore increasing the resistance.
I also should have been more careful about making sure the wire was taught when I took the readings because if it was loose it would have been a longer length that the one I thought I was reading.
Evaluation
From my graph I can see that my results that I collected are very reliable. I know this because my graph does not show any individual anomalous results. I can see on the graph that none of the results plotted are anomalous because all the points lie along the same straight line.
When I was measuring the lengths of the wire, my measurements might have been slightly inaccurate as the rulers used might not have been exact, and it was difficult to get an accurate reading of length by eye, as the wire was not completely straight, so it may have been of different thicknesses throughout the length. This would have contributed as a slight error in my results. As this factor probably only made a slight difference, it did not affect my results. Most errors in our experiment were encountered in the measuring of the wire. This is because it simply was not very practical to hold a piece of wire straight, whilst holding it next to a ruler and then trying to accurately fix crocodile clips to the right part on the wire. Also I do not feel that the crocodile clips were always fixed securely to the wire with a good connection. This also meant that they were easy to move about on the wire changing the length of it. Errors rarely occurred in the setting of the current and the reading of the voltage. It was just in the preparation area that they did occur. Another example of this is the wire was never totally straight when we started the experiment, which may also, as said earlier on, affect the resistance of it.
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
The crocodile clips and the connecting leads could have affected the fairness of the experiment. They are a different type of metal from the wire and may have different properties and therefore different resistance.
