Current is the rate or measurement of the rate of flow charge, which has decreased in speed, therefore, means the current has decreased and the resistance has increased.
In the experimentation there is another problem that could cause resistance in the wire the problem, which could occur, is the heat. This is because the material of the wire is copper 26 SWG. And copper is known as a good metal because it is a good conductor of heat and electricity. Heat in the experiment that I will be dong will cause friction between the electrons and the atoms of the wire. Copper is also known as a negligible metal because a proportion of its atoms are free to move around from atom to atom. Heat will speed up the movements of the particles causing these atoms to vibrate fast. As the electrons in the current are flowing through the circuit as they reach the wire, there will be friction between them and the atoms of the wire (it would be like someone walking right up to you and going side to side of you very fast and you would not know when to move).
To prevent this from occurring, in the experiment I will turn of the power pack whenever it is not in use.
If I were to plot a graph to show how resistance is related to length of the wire I would expect it to look like this:
Resistance
What you can see from this graph is that, as the length increases so does the resistance.
Length
Apparatus
- Power pack
- Wires (connecting the circuit)
- Ruler
- Copper wire
- Ammeter
- Voltmeter
Method
- Measure your 6 lengths of wire: 10cm, 20cm, 30cm, 40cm, 50cm, and 60cm.
- Go and take your equipment and set up your circuit as the one shown below.
- Place the 10cm wire where shown on the diagram above, making sure it securely attached to the voltmeter and ammeter the voltmeter should be placed in a parallel circuit to the rest of the circuit.
- Switch on the power pack (keeping it on the same level throughout this whole experiment).
- Get the most common reading from your voltmeter and ammeter.
- Record your readings clearly in a table, which you can understand what you have written.
- Repeat steps 3 to 7 with all the 6 lengths.
- After this repeat all your lengths again to see whether you get a similar readings to what you have already done
Results
The results of the of the experiment are:
These are the average results we got for the experiments that Claire and I made, we done the first experiment and then we took the circuit apart because we wanted to make the test a fair test and we needed for the to cool down so that no heat was going to build up and stop us from having the fair results we needed. Although we did take these precautions to help us get fair results such as turning the power pack on/off when we had finished making a length results. Ben managed to walk through our experiment and dismantle the whole things, which may explain why the second pair of results is slightly different from the first, disrupted our results. The results of the first and second experiment are:
The first experiment readings:
The second experiment readings:
Conclusion
My conclusion for my experiment is that the longer the coppers wire the more resistance there will be. The reason why the resistance increased when the length increased is because the length was proportional to the resistance. This means that if the length increased so will the resistance and for the resistance to increase the length will have to if none of the other factors that effected resistance in a wire were happening to this experiment. If the electrons of the current were circling a small-wired circuit they would only have to feel resistance for a short amount of time, but if the electrons of the current were going through a long wire they would have much more collision in the circuit than a smaller-wired circuit.
My prediction was proved correct with the experiment that I did twice to ensure my results were kind of right. Although my results were not identical they still proved that my prediction was right.
There are many reasons why think the results above were not identical; I think Ben was one of the reasons when he walked through the middle of our experiment destroying everything and dismantling it and causing problems. Things that may have also affected are the factors that I mentioned above for example; Heat in the experiment that I will be dong will cause friction between the electrons and the atoms of the wire. Copper is also known as a negligible metal because a proportion of its atoms are free to move around from atom to atom. Heat will speed up the movements of the particles causing these atoms to vibrate fast. As the electrons in the current are flowing through the circuit as they reach the wire, there will be friction between them and the atoms of the wire (it would be like someone walking right up to you and going side to side of you very fast and you would not know when to move). Although Claire and I tried to prevent heat from building up there were times where we forgot to turn the power pack off.
Resistance building up from other factors in stead pf length did prove to get in the way but the mostly all the resistance was because of the length of the wire length. In my prediction I didn’t predict what I thought the resistance was going to be for each length of my experiment. But a rough guide of what would have been good if I predicted it would have been:
- 10 cm= 1 ohm
- 20 cm= 2 ohm
- 30 cm= 3 ohm
- 40 cm=4 ohm
- 50 cm= 5/6 ohm
- 60 cm= 7 ohm
Evaluation
Overall I think that the experiment was done to the best ability and the prediction was researched for really well as I tried my best to really research everything to the best I could. Some of the places that I used to research my factor length were the physics textbook by OCRA this book was used just to collect the basic information of what would affect the wire in terms of resistance, an A-level textbook this was used to find the resiseivity of copper wire. I also went on the Internet to research what I had written in my prediction and also went to check out if had missed any important things in my prediction, which you will notice that there are extra stuff in my prediction. I went to the website to help with my to get the extra information.
I do think I could have done this even better in this experiment or coursework, I don’t think I tried hard enough to produce the right results for example when Ben dismantled our circuit we didn’t think of trying again and just made the circuit again and carried on. And as well as taking loads of precautions to stop resistance creeping up in other ways than length heat may have built up in the circuit.
If I were to change anything I would do the other factors because I would like to see which factor was the easiest.