Detailed Plan: -
To make the experiment a fair test, I will use the same voltage throughout the experiment on every length of wire.
The equipment I will use for the experiment is: -
- Nichrome wire.
- An Anmeter (to measure current).
- A Voltmeter (to measure voltage).
- Power Pack.
- Crocodile Clips (to hold piece of wire).
- Other wires (to make the circuit for the experiment).
- 2 metre rulers (to measure the Nichrome wire).
The Nichrome wire I will use will be cut from 140cm to 50cm. The Nichrome wire will be taped to 2 metre rulers (1 metre ruler when wire is less than 1 metre (100cm)). The wire will then be connected to a voltmeter and an anmeter in the circuit with the voltmeter in parallel and the anmeter in series. This is how the circuit will be set up: -
Anmeter
+ _ + _ Batteries (4 Volts)
Other wires for circuit
Voltmeter
Nichrome Wire On
Two 1 metre rulers
The crocodile clips will then be connected to the Nichrome wire which are on the two 1-metre rulers at 140cm to 0cm. The power pack will then be turned on. I will record the voltage and current in a result table and then reduce the wire by 10cm for the next set of results (e.g. the lengths will be 140cm, 130cm, 120cm, 110cm, 100cm, 90cm, 80cm, 70cm, 60cm, and 50cm). The experiment will be done repeatedly until the wire is cut to 50cm.
We can’t go any lower than 50cm because the wire may get too hot and will burn and maybe melt the wire, which could break the circuit and ruin the experiment. The experiment will be repeated twice at each measurement to make sure the results are accurate.
After the experiment I will divide the voltage by the current to get the resistance and then I will draw a graph.
Results Table (First Attempt)
Results Table (Second Attempt)
Conclusion
As you can see from the result tables, you can see that when the wire is at the length of 140cm, on both attempts, you can see that the resistance is high, the voltage is high and the current is low. When the wire is the length of 50cm, on both attempts, the resistance is low, the voltage is low and the current is high. The reason this has happened is probably because when the wire was at 140cm, on both attempts, there was more resistance because there was more particles in the wire to help slow the current down; air resistance also helped slow down the current. But when the wire length was at 50cm, the wire was shorter than the 140cm length so there was less air resistance to slow down the current and less particles in the wire as well, so the currents goes faster. You will see the difference on the graphs of both attempts where you will see that the line slopes downwards, which means the shorter the wire the less resistance there is.
From all this evidence it proves that my prediction was right and that the shorter the wire the less air resistance and the less particles there are in the wire so the current runs smoothly. It also proves my prediction was right from that the longer the wire the more air resistance and the more particles in the wire, which means the current, will be much slower.
Evaluation
From the results I have got I am very pleased with them since they are right and have helped me prove my prediction was right. But there was one result, which was a bit anomalous; this was the result from when the wire was at 120cm. You will see this anomalous results ringed on the graph. I think the reason I got this anomalous result was because the rulers I had to measure the length of the wire were taped together and the measurements were a bit awkward to read by the part where the tape was. Another reason why the result was anomalous could be because the tape may have caused resistance in the wire causing the current to be slower.
The ways, which I could use to improve my experiment, would be to get a two-metre ruler so that I won’t have to tape to one-metre rulers together. Another way in which I could improve my experiment could be to leave the wire to hang freely without the ruler underneath it so that there won’t be resistance being caused in the Nichrome wire from the ruler.
The evidence I have got is reliable enough to support the conclusion since there is only one anomaly and that the results from the tables are perfect enough to make a suitable graphs to show how the length of the wire affects the resistance in the wire.
Further work in which I can do to see how wire affects the resistance by seeing if the tubing around a wire has any affect on the resistance and for this experiment I could use wires with different thickness of tubing. Another experiment I could do for seeing how the wire affects the resistance by changing the voltage to see how the voltage affects the resistance in the wire.