Fair test
All things need to be kept the same in an experiment except the one key variable, in this case the length of the wire. That will change every time I record another reading. To make the experiment a fair test I need to keep the same piece of wire, because different wires have different resistance, use the same connecting wires for the same reason. I will disconnect the circuit every time so the wires wont heat up. If the wires heat up then the atoms gain more kinetic energy increasing the resistance. Every component of the experiment as to be kept the same apart from the length of the wire this is because different components will have different resistance.
Knowledge
In 1899 J.J Thomson discovered electrons. Moving electrons are an electric current. Electricity flows in metals. Metal wires are made of millions of tiny metal crystals Each crystal’s atoms are arranged in a regular pattern. They are free electrons and don’t stick to any particular atom.
The diagram above shows how an electric current works. A potential difference makes the free electrons move along. They accelerate until they bump into an atom. They then repeat the process. This results in them drifting along with a low average speed of 2mm/s.
Some conductors are worse than others. This is because they have more resistance to current. The free electrons keep bumping into atoms. It also depends on the wires size The thicker the wire the lower the resistance this is because there is more space for free electrons to move without colliding with the metal atoms. Thickness is just one of four factors affecting resistance, the others are the type of metal the wire is made of different metals have different levels of resistance. The temperature also affects resistance, the hotter the ire the greater the resistance this is because the metal atoms gain more kinetic energy when the temperature increases. The final factor is the length of wire, this is the factor tested in my experiment. The longer the wire the greater the resistance.
Analysis
My results tell me that as the length of the wire increases the resistance increases too. For each time that the length of wire goes up in 10cm the resistance in ohms goes up 0.08 Ohms. This is because as the wire gets longer the resistance will get proportionally greater, this is because the electrons have a greater distance and greater time to travel giving a greater probability of colliding with the wire atoms. This is the cause of resistance, when electrical energy is turned into heat energy.
Also, electricity flows in metals. Metal wires are made up of tiny metal crystals. Each crystal’s atoms are arranged in a regular pattern. The metal is full of ‘free’ electrons that do not stick to any particular atom. They fill the space between atoms in the metal. There is an electric current when these electrons move. Free electrons move when there is an electric ‘pressure difference’ or potential difference. This conclusion supports my prediction.
Evaluation
My results prove that the longer the piece of wire the greater the resistance. I have compiled a good set of result, My results were very good. I had no anomalies. The procedure we used during the experiment was very good; I know this because we had no anomalies. We could have made our results even more accurate by doing each measurement of wire 5 times rather than 3. The procedure we used was extremely effective and showed the predicted results almost perfectly. If I had to change any part of the experiment procedure I would repeat each length 5 times instead of 3, this would give me a more accurate results. The wire that we used for the experiment was bent, which means it was probably more than 10cm for example when we measure 10cm. A straight wire would give more accurate results
I don’t have enough results to support a firm conclusion, to firmly support a conclusion, I would need to perform the experiment in various ways, e.g. change the thickness of the wire and could maybe use different types of wire. I also could do more varying lengths. However I have looked at other group’s results and I can confirm that every other group had similar results and came to the same conclusion.
