I predict that the longest wire, which is fifty centimetres, will have the most resistance and the shortest wire which is twenty centimetres will have the least resistance. The resistance should gradually get lower as the wires get shorter from fifty centimetres. This is because the electrons have to pass through fewer atoms, which they get obstructed by.
I am using Nichrome wire for my experiment. This is an alloy, made of Nickel and Chrome. It is a conductor. In metallic conductors the atoms are not so tightly packed together. This allows the free electrons to move around a tiny bit.
The diagram above is showing these free electrons moving around when no potential difference is running through the wire. The free electrons just pass from atom to atom randomly. Although when the wire gains potential difference the free electrons are forced to flow the same way, i.e. the current. The diagram below shows this.
On the way through the wire some of the electrons get obstructed/blocked by the atoms. But the ‘push’ of the current still forces the electron forward. This is what causes the resistance in the wire.
The movement of the electrons through the conducting wire to a battery is the electrical current. This means the current is not ‘made’ in the battery, it is already in the wire. It is the flow of electrons already in the wire. The battery only provides the push to get the electrons moving in the same direction.
Analysis
Looking at graph one it shows that the longer the wire is the more voltage is present This is because the longer the wire is the more free electrons it has. Therefore you will need more voltage to create a bigger current to push these electrons round the circuit.
The pattern shown in the second graph is the longer the wire is the greater the resistance is.
The atoms in the wire mostly affect the resistance. When the electrons past through the wire they were blocked by the atoms.
In a 25-centimetre wire it would have, for example 1,000,000 atoms but if you double the length to 50 centimetres it would have 2,000,000 atoms. As I said above the atoms affect the electrons by blocking them. This causes resistance and it is why a long piece of wire has more resistance than a shorter one.
Here I will use a calculation to prove that if a wires length is doubled the resistance is approximately doubled. I will use a twenty centimetres and forty-centimetre piece of wire for my example. I am using my proper results.
Average resistance of 20cm wire- 1.4978 ohms
1.4978 ohms times 2 = 2.9956 ohms
Average resistance of 40cm wire- 2.89702 ohms
2.9956 ohms – 2.89702 ohms = 0.09858 ohms
As you can see above if you double the length of the wire the resistance is almost doubled. This is the reason resistance went up as the length of wire went up.
This experiment was very quick, efficient and simple to set up. It was very quick to do the experiment and get the results as well. We got all of our results in around half an hour
Most of our results were very good in the way of quality. Apart from a few odd results, due to over heated wires possibly. When all the results were averaged and put onto graphs we had one anomalous result, 2.85 ohms. This was out of line compared to the line of best fit.
As one of my results stands out as anomalous I would do that length of wire again, forty centimetres. I would hope to get around 2.95 ohms for my new result. I would re-cut my wire to the acquired length and do the experiment again. I would then take my results, put them in table; average them and them plot them on my graph. This would then fit my line of best fit if I got the result I hoped for.
Most of my results are reliable. They fit my line of best fit well. Apart from the one anomalous result as I have mentioned. As I said I will do this length of wire again to get a better result.
In order to get absolutely perfect results I would do my experiment again but put my lengths of Nichrome wire in a beaker of cold water while they are connected and I am doing the experiment. This makes sure the wire does not heat up as you conduct the experiment, as this heating up causes odd results. The wires stay at a constant temperature making sure your results are more accurate. I would set the experiment up as below.
Lloyd Emery
