Using this triangle I can produce the following formula:
R = V / I
Resistance = voltage / current
I will record the results three times so that the final result is reliable. I will start my recordings at 10cm’s and then add 5cm’s each time.
Safety:
To ensure that the experiment will be safe I will place the measured wire under water so that it does not overheat. I will also wear goggles when power is applied to the circuit.
Prediction:
I predict that the longer the wire, the more resistance there will be. I believe this because if the wire is longer then there is more material for the electrons to get through thereby increasing the resistance.
Apparatus:
I will use the following equipment in my experiment:
Circuit Diagram:
This is a circuit diagram of my experiment; at the top of the circuit is the symbol for the battery which in my experiment is the power pack. The A represents the ammeter and the V represents the voltage meter.
Conclusion / Evaluation:
From the graph I can see one very clear trend, which is, as the length of the wire increases so does the resistance of it. Another, more significant thing is that it the increase is constant. This is indicating by the fact that the line drawn is a straight one.
I think that from my results I can safely say that my prediction was right. The resistance did change in proportion to the length. This is because as the length of the wire increased the electrons that made up the current had to travel through more of the fixed particles in the wire causing more collisions and therefore a higher resistance.
I feel that overall our results were quite accurate. This is can be seen when we look at the graph, which shows a straight line with all of the points.
Improvements:
I would make the following modifications to improve the experiment if I was to do it again.
Instead of connecting the voltmeter to the main circuit I would connect it to the wire which is being tested. I would do this so that the voltmeter is measuring the voltage of just the wire being tested and not the wires of the main circuit as well.
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.
