- A wooden plank with one nail at both end and wire running from end-to-end.
- One ammeter and one voltmeter.
- One power pack. [From preliminary work].
- One batter to supply power.
- A metre ruler for measuring distance of the wire.
- Wire and crocodile clips to connect the circuit.
Once I have my findings from the investigation, I will use them to plot and annotate a simple graph/series of graphs.
I believe my plan is a good way of carrying out this investigation, as it helps me to keep the test as fair as I see possible, which in itself is in the interest of science. My scientific reasoning for believing my method is correct is that, as length will increase the amount of resistive atoms that the electrons have to pass through for the circuit to work will also increase. I also think that with the way in which I am conducting the experiment, there is only one factor I can think of which may affect my findings, this happens to be human error.
My circuit will need to look like this:
As you can see by my diagram, the ammeter is in series with the circuit, and the voltmeter is aligned in parallel.
The wire I am planning to use in the circuit is, a metal known as Constantine.
I believe that, my findings will show that the length of a wire does affect its resistance because, as length increases, the amount of resistive atoms that the electrons have to pass through for the circuit to work will also increase. I believe that that my graph will show that resistance increases with the length of a wire in circuit. In my opinion this will be caused by, an increase in resistant atoms inside the wire, as length will increase mass.
For my preliminary work, I originally used a power pack as the power source for my circuit. After which, my findings and graph suggested that this power source was unreliable, so I opted to change my circuit’s power source from a power pack [AC], to a battery [DC], hoping for a better result.
Preliminary Work
For my preliminary work, I was trying to see the same thing as in this For investigation, which is, does the length of a wire have an affect on it’s resistance and I was also seeing whether or not the equipment I chosen to use would be able to do the investigation properly.
The equipment I chose to use was:
- A wooden plank with one nail at both end and wire running from end-to-end.
- One ammeter and one voltmeter.
- A metre ruler for measuring distance of the wire.
- Wire and crocodile clips to connect the circuit.
After carrying out my preliminary work, I decided that using a power pack was not reliable enough. I then had to think of what I could use as a new power source, which would be reliable and help me to collect a fair reading. I decided to change my power source to a battery pack [DC] as it would give a fairer reading for my results and lower the chance of collect anomalous data.
Observation
To make sure I get fair results I intend to collect them in a safe and secure manner. I will also use a chosen range for my results. The range will be ten centimetres per reading. I will use three wires for this experiment. My ammeter will be set at DCA 20cm over 10A.
My voltmeter will be set at DCV 20. My results from the readings will be repeated and an average worked out before plotting my graph.
All resistance results on the graph are the average reading for its distance.
[Figure 1.2]
Analysis
I have taken my results table [figure 1.2] from the investigation, and plotted a graph with a line of best fit. [Figure 1.1]
I have overseen my results and using them, I am going to draw a meaningful conclusion for this investigation.
After referring to evidence taken from the results I gained during this investigation, I conclude that, my prediction of length being a key factor in resistance was correct. This in my opinion was correct because my readings taken show that as length increased so did resistance, and further reasons for believing so are that, my graph was correct and the only anomalies I encountered were more than likely due to a slight human error.
The evidence and my prediction coincided and were well matched. This you can pick up on by yourself, simply from looking at the graph [figure 1.1] and my results table [figure 1.2], because you can see that there is a definite trend in the pattern on the graph.
Evaluation
The only results that did not seem to fit in with my prediction were, the results recorded from eighty and ninety centimetres. The reasoning for the anomalies of these particular results is due to a slight human error as predicted. This human error derived at the recording of results, it was hard to record them at the exact distance from the crocodile clips at all times, leading to produce a slight human error.
I believe I have enough evidence to prove the conclusion, which I have drawn from my recorded results during the investigation. This conclusion is that length does increase resistance in a wire, due to an increase in resistive atoms proportional to the mass. My graph and table shows that there is indeed a trend/pattern in the results, and that resistance clearly increases as we increase the length of a wire in a circuit.
The ways in which my investigation could have been improved would lie in the method. I say this because, my method could have been slightly more defined, and reduce my scale for readings taken to a five-centimetre scale rather than the original 10 cm used for the investigation. That would have enabled me to collect clearer results, as my range would be wider, enabling the results to be fairer and an easier to work out average. I do still believe however, that my method was of enough use to me for conducting my investigation and being able to draw a meaningful conclusion from the results, which I gained in the process. My theory from my introduction was after all proved correct and I did manage to prove that resistance increases with the length of a wire in a circuit. This increase was due to a build up of resistive atoms inside the wire in parallel with the increase of mass. If I were to conduct this experiment again, the main area I would focus on changing rather than my scale would be to try to be more precise in where I took my readings from, and try to keep all readings from the same distance away from the crocodile clips.
