Wires (to connect to power pack, ammeter, voltmeter etc..)
Ruler (Measure our 5 distances, 5cm, 10cm, 15cm, 20cm and 25cm)
Step 2 - Connecting all the equipment together
Step 3 - Start the test.
We have to do the test on each part of the wire 3 times. We do this to make sure that we get around about the same result in current each time.
Step 4 - Once the test has been done we shall record our results down. With these results, we have to divide the voltage by the current to get the average resistance in each result box. This will then be converted into a graph.
Diagram on next page.
Test Results
These are my test results from our experiment:
Voltage always 2.50 A= Amps
5cm 10cm 15cm 20cm 25cm
A 5.48 A 2.80 A 2.00 A 1.43 A 1.26
A 5.83 A 2.83 A 2.06 A 1.41 A 1.28
A 5.66 A 2.82 A 1.99 A 1.42 A 1.23
Now what I have found my results, I have to work out my average resistance for each. I do this by dividing the voltage by the current, I do this for all three results that I get per each measurement. Below are my results, with the calculations:
5cm
2.50V / 5.48 = 0.45
2.50V / 5.83 = 0.42
2.50V / 5.66 = 0.44
0.45 +
0.42 +
0.44
----- 1.31 divided by 3 = 0.43
1.31 Average resistance for 5cm is 0.43
-----
10cm
2.50V / 2.80 = 0.89
2.50V / 0.88 = 0.88
2.50V / 0.88 = 0.88
0.89 +
0.88 +
0.88
----- 2.65 divided by 3 = 0.88
2.65 Average resistance for 10cm is 0.88
-----
15cm
2.50V / 2.00 = 1.25
2.50V / 2.06 = 1.21
2.50V / 1.99 = 1.25
1.25 +
1.21 +
1.25
----- 3.71 divided by 3 = 1.23
3.71 Average resistance for 15cm is 1.23
-----
20cm
2.50V / 1.43 = 1.74
2.50V / 1.41 = 1.77
2.50V / 1.42 = 1.76
1.74 +
1.77 +
1.76
----- 5.27 divided by 3 = 1.75
5.27 Average resistance for 20cm is 1.75
-----
25cm
2.50V / 1.26 = 1.98
2.50V / 1.28 = 1.95
2.50V / 1.23 = 2.03
1.98 +
1.95 +
2.03
----- 5.96 divided by 3 = 1.98
5.96 Average resistance for 25cm is 1.98
-----
My Conclusion
Looking at my results, the prediction I made was correct.
My prediction was that the longer the wire, the more resistance would be applied. This can be seen from my average resistance results in my graph and on the 'Test Results' page.
Looking at my graph, I can see a graphical trend. This trend, even though is not straight, seems to evaluate the results of other areas of wire. If my results would have been more accurate, the plot points on my graph would have gone in a straighter line.
This would have also have evaluated other areas of wire, without doing the test at that part of the wire. The reason my plot points were not in a straight line could have been because of the following things:
- The voltage (2.50) wasn't exactly the same each time
- The readings were taken quickly for the first measurement (5cm) as the wire kept getting hot and so we may not have got completely accurate results.
- The measurements, although seemed accurate, may have not been completely correct.
Correcting these problems will most definately improve my line of best fit and the graphical trend will seem more obvious.
Evaluation
To improve my experiment, I could do the following things:
-
Do the experiment again. This time round, I will take note and try to achieve the above pointers (in my conclusion) so that I can get more accurate results and a better understanding of the test.
- Try the experiment on a different type of wire, such as thicker, longer, shorter and even a different material. This would be for a much broader understanding of the resistance in different types of wire. This would almost certainly differ from my own results as the wire would be different to the one that I used in the test.
I could also try to be more practical and do the experiment more times and more carefully, i.e safer, slower, measurements carefully and voltage the exact same each time.
To get the 'perfect result', I could compare my results with other people results and see who is closer to getting the most accurate line of best fit; this would also correct any anomalies in my graph and would give me a better overall result.
