The equation for this experiment is:
Resistance = voltage
Current
Fair Test
It is essential to perform a fair test the particles inside the wire are not affected by different states. I will keep this test fair because if I don’t then the particles inside the wire would be affected by different states e.g. if there was longer wire the resistance would change a bit and if the temperature outside changes it would affect the metal to change it and the particles inside it.
Prediction
Before the experiment I predict that the longer the wire is, the lower the current meaning a higher voltage resulting in a higher resistance. This occurs because there are many different types of particles in a piece of wire and not all are electrons. For example many of the particles are not electrons at all and will not collect energy being passed on from the charged electron so the electricity is simply wasted and lost. This will reduce the current which results in a higher voltage etc
In the experiment we will use an ammeter which will be used in the experiment to measure the current. The current is the electrical flow of charge. The resistance in the wire can be found by finding out the voltage and dividing it by the current.
Ohms law states that the voltage over the conductor is relative to the current as long as the temperature is kept constant. In our experiment our fair test says that we will keep the temperature the same. Therefore our results are ohmic
Types of wire.
Pre-Test Test Results
Results
Our group has decided that we are going to investigate what effect the length of the wire has on the resistance using Constantan 32. We have decided to use this wire because unlike other wires the current stays the same no matter what length it is, as you can see from my results table above.
To achieve a good range of results I am going to use a selection of lengths, the difference between these lengths will be 5cm and the longest length of wire is going to be 50cm. This range will ensure I will get an sufficient range of results that will show a good legend in my graph, confirming my prediction.
To maintain a fair test I must keep the distance between each length of wire the same. This is important to avoid distortion on the graph otherwise it wont show up properly on the graph and could distort it.
Analysis
By examining the graph on the other page I can see that the prediction I made before the experiment was correct, my prediction was that as the length of the wire increased the resistance got bigger as well. The graph shows a very strong positive correlation as all the points marked out are in line. This result is due to the ohms theory that the length of the wire is directly proportional to the resistance created. The longer the wire the higher the resistance and the shorter wire the lower the resistance. I think this because the longer the piece of wire the further the electrons have to flow, then that would mean the more collisions with atoms, which would increase the energy therefore increasing the resistance. Also if I double the length then I double the resistance. The electrons start of with kinetic energy they then collide with other electrons, which is then transferred to heat energy.
I think that the shorter the wire the lower the resistance because they have less of a way to travel which means they wont collide with as much atoms, therefore less energy will be produced.
Evaluation:
As illustrated in my graph I seem to have 2 anomalous results. this demonstrates that my results were not as accurate and reliable as they could be. This also means I must have not kept a fairly good fair test. I got quite good results because my experiment was suitable for this experiment as I can see on the graph ex. There is a few reasons why I may have got anomalous results in my test. There is the possibility that the batteries may have just been running out so were on low power or the wires had a small fault in them. This would mean the current was not as big which would affect my results. Therefore that means if we changed the experiment in some way it may have caused it to become less accurate. If we had the resources then we would use all new equipment to perform out experiment e.g. new batteries, new wires, and new ammeter/voltmeter. As this was not possible we had to use the materials we had, this could have been the fault in our experiment. As always, if we had more time then we could perform the experiment over and over again with the same lengths to get a more accurate result, this would also give us a much better range of results for each length because just one or 2 for each is not as reliable as 10 for each for example. This would result in so many decimal places that there would be no point. We could also do longer lengths to prove the theory that length is directly proportional to the resistance. If we had dome the experiment
