Prediction:
I predict that the longer the length of wire the higher the resistance. This is because the longer the length of wire the more free electrons will collide with other free electrons, this means that the more collisions the more heat energy will be lost.
Method:
The following circuit was constructed to perform the investigation.
A
V
The dotted line represents the constantan wire in the circuit.
We first fixed the 60cm length of constantan wire to a wooden board with two metal clips on; the wire was fixed into place and was ruled off every 3cm. We then added the ammeter, voltmeter and power pack into the circuit and connected them accordingly. The voltmeter was only connected at one end so we could use the other end to record the voltage every 3cm. We attached the voltmeter to the 3cm marking and recorded the voltage; we then did the same at 6cm and so on.
Safety:
In order to carry out a safe experiment we chose a low voltage of 9V to minimise overheating. We were careful to not touch the wire whilst we were recording data, because the wire might have been hot.
Results:
We then repeated our experiment
I then made a table out of the averages and calculated the resistance.
Conclusion:
As predicted, an increase in length resulted in an increased resistance. The length of the wire is shown to be directly proportional to the resistance, if you double the length of the wire you double 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.
Evaluation:
From my results table and graph I can see that my results that I collected are very reliable. I know this because my results table does not show any individual irregular results this means that I did not have to leave any results out of my averages because they were irregular.
To improve on my results I would use a digital voltmeter instead of an analogue meter. I would do this because a digital voltmeter is a lot more accurate than an analogue because if the needle in the analogue voltmeter is bent then the readings given off will be false whereas a digital voltmeter does not rely on a needle or any other manual movements.
As well as making this modification 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.
