Voltmeter
Equipment List
Ammeter
Voltmeter
Lab pack
Wire
Ruler
Crocodile clips
Method
The equipment will be set up as shown in the diagram.
I will cut a piece of wire 1 metre long and attach it to the metre ruler using Blu-tack. I will set the lab pack at 0.27A, as indicated by the ammeter, which will be attached in series on the 0cm point on the ruler. I will then attach the voltmeter in parallel across the wire by also using crocodile clips at every 10cm along the metre ruler. I will take five readings for each length, from the ammeter and voltmeter and then using the formula,
V (voltage) = I (current) * R (resistance)
I will transpose the formula to calculate the resistance.
R = V
I
I think that my plan and the equipment used will be a good way of carrying out this task and obtaining a good set of results, because I will be using a digital ammeter and voltmeter, a metre ruler so that my measurements will be fair each time. The ammeter will be connected in series to determine the current flowing through the wire and the voltmeter will be connected in parallel so that it only takes the voltage reading across the wire. I will make sure that the thickness of the wire will be the same each time. By doing this I will be able to make sure that the reproduce ability is as close as possible, so that I can make any improvements so that there are no anomalous results.
Results Table
Analysis
From the graph I can see that the results are shown on a straight line and the line is continuous, this shows that my results are proportional, whereby the resistance increased by 2ohms each time and the length of the wire increased by 10cm each time. My prediction (which was as the wire lengthens so does the resistance) was correct. The reason for this is that at 50cm the resistance was 10 ohms whereas at 10cm the resistance was 2ohms.
Evaluation
I think that this investigation went quite well under the experimental conditions. The results were adequate to plot a graph, which enabled to draw a firm conclusion. There were some experimental errors but the points still fit exactly on a straight line. There were no anomalous results. The current occasionally varied by 0.1A. This is could be because the wire was kinked in places causing the digital ammeter to flicker when measuring. The results are quite reliable to some extent, whereby I proved that my prediction was correct. However the results maybe unreliable whereby wire might not have been measured accurately, therefore there would have been some inaccurate readings.
If I were to repeat the experiment, to reduce the experimental error I will stretch the wire out completely so there are no kinks and sellotape it at 10cm intervals along the wire so that it is kept straight. To extend the enquiry I would investigate with different thickness of wire, whereby I would do the same experiment and investigate if the thickness of a wire affects its resistance.
