Apparatus
Voltmeter Ammeter
Wires Power pack
Crocodile clips
Preliminary Diagram
Preliminary Method
- I will start by setting up the apparatus and connecting the wires to the piece of wires, voltmeter, and ammeter.
- Attach the crocodile clips the wire but do not change the length of the wire as in this preliminary experiment.
- I am investigating how voltage effects the heat produced, which changes the resistance of the wire.
- Therefore in this experiment I am trying to establish a stable temperature to use in my final method of my investigation.
- I will keep changing the voltage of the wire and make observations of the temperature change of the wire in the circuit.
Safety
- Must keep plug of powerpack away from any water.
- Always use a safe voltage.
- Always make sure electric equipment is switched off after use.
Preliminary Results
Voltage Comment on Temperature Voltmeter Ammeter
Reading Reading
1 no change 0.01 0.01
2 slightly warm 0.19 0.09
3 warm 0.42 0.22
4 warm 0.67 0.35
5 increased warmth 0.92 0.48
6 quite hot 1.14 0.6
7 increased heat 1.4 0.73
8 very hot 1.66 0.88
Preliminary Conclusion
In my preliminary experiment I found that the voltage of the circuit produced heat so we had to find the best voltage to use in the final method of the experiment. It is important to get the right temperature as it affects the resistance, so it is important to try and get the temperature stable.
In our results I found that the higher the voltage the hotter the wire became, this is because the greater the voltage the more electrons are being pushed around the wire causing the heat to increase. This occurred with voltages such as 5,6,7, and 8. You can see these results set out on the table on the previous page. So in conclusion to this I know that in my experiment I will use quite a low voltage, i.e. to produce a stable temperature. Therefore I will use a set voltage of 2 volts on the powerpack.
Final Diagram of experiment
Method
- I will start by setting the apparatus up as shown in the diagram above. This will include a voltmeter, ammeter, crocodile clips, connecting wires, length of wire, and a powerpack.
- Then start by putting the crocodile clips at two particular measured points, and by using both an ammeter and voltmeter use these readings to calculate the resistance of that particular length of wire.
- Then change the length of wire a number of times and record the results on a table as accurately as possible to collect the most reliable results.
- I will have a powerpack set at 2 volts and take measurements at:
10cm
20cm
30cm
40cm
50cm
60cm
70cm
80cm
90cm
- I will increase the voltage so I am able to investigate the differences in measured resistance. I will take measurement every 10cm to achieve a set of accurate results.
- Then I will compare and contrast the results that I collect with my prediction and see if what I thought would happen did? And if not, why not? I will be able to refer back to my prediction and see if my prediction that the resistance would increase in the wire as the length does. My theory being that more collisions of electrons would occur as they would have more energy to collide with each other. Hopefully I will conclude with a set of results to support my theory
Result tables to show sets of results
Conclusion
I found in my investigation that my earlier prediction was correct. The longer the length of wire the more resistance is produced. I have shown this in my results tables and you can clearly see the pattern/trend occurring as the length of wire increases so does the amount of resistance that I recorded.
On the previous pages I have drawn a table to explain the results I obtained by measuring the readings on both ammeters and voltmeters at individual lengths on a piece of wire. I recorded two sets of results at each measurement so I would be able to collect a more accurate and reliable set of results to plot on a graph. I then calculated the resistance by using the formula:
Using this I calculated the resistance for the first set of results then the second set, then I worked out an average resistance for each individual measurement at each set voltage of 1-4. You can see this clearly on my table.
On my graphs you can see the measurements I took show an increase in an almost straight line suggesting a reoccurring pattern using voltages 1-4.
I can conclude that as a length of wire doubles so does its amount of resistance, which explains the straight-line trends I found on my graphs.
I found that my graphs showed no anomalous results and my collected results showed consistency conveyed on the graphs.
You can also see from the graphs I have drawn to show my results that the pattern that occurs shows that as the length of the wire increases so does the amount of resistance this is because the longer the piece of wire the more collisions between electrons in that longer piece of wire. The collision increase as they are given more energy to bang and bump into each other producing more collisions, i.e. more resistance in the wire.
My results co inside with my prediction that the longer the piece of wire the more resistance produced as the electrical current passes through the wire it takes more work for the electrons to pass through.
You can see how this has occurred on my graphs, for example on the graph showing my results at 2 volts, the longer the piece of wire the increased resistance was recorded. You can see clearly how the results occurred in a perfect straight line of best fit. This occurred in most of my results from 1-4 volts. The line of best fit wasn’t always perfectly straight but the general trend increases in a general increasing line going up in amount of resistance recorded.
From the evidence I have found I can conclude that if I were to want to predict further results it would be possible and most reliable. This enables my to use what I found in my investigation and use it for further investigation.
Evaluation
In my investigation although I made some earlier mistakes in my preliminary work I took his concluded information and made changes to my method. The final method, which I used in my final experiments, proved to be successful and most efficient.
I can see from my results that they were quite accurate and therefore reliable as my graph almost shows a straight line of results. This concludes that my results were accurate and were reliable enough to make further predictions from. I did not record any anomalous results, measurements were all quite consistent. You can see in reflection of my results that as the electrons collide with atoms as they pass through the conductor although the electrons lose some energy the atoms gain energy and vibrate faster. The vibrations increase at a faster rate, which causes the increase in temperature, which you can see on my graphs.
Possible proposed improvements that I could make such as if I were to look at the efficiency of my method/procedure I would most certainly look at areas where mistakes could have been made. For example I was not able to carry out all of my experiments at the same time, therefore different equipment. Using different ammeters, voltmeters, wires, etc. could have an impact on the reliability of my results. So I could look into making sure all experiments were carried out in the same period of time using the same equipment. Human errors could also be made when recording results, which is always a possibility. So I would simply have to try and be as accurate as possible in the future.
The above improvements would make the evidence gathered much more reliable. In this nature of investigation reliability is a key factor as it can affect your results substantially. Improvements can always be made but sometimes human error and be a factor but it comes down to precision and accuracy to be taken most seriously.
Although there were no anomalous results found from my experiments it showed the reliability of the evidence I have found to support my conclusion that the longer the piece of wire the more resistance is produced.
Finally, with the evidence I have collected I can support my final conclusion that there is a definite relationship between the length of wire used and the amount of resistance produced
If I were to take the investigation further I could possibly look at the type of wire used which I mentioned earlier in my background information on resistance and its effects. I could also carry on with the idea of heat and its effects on resistance which was an issue I touched in my preliminary work when I investigated what voltages were the most appropriate to use in the investigation.
Additional evidence which I could possibly produce to support my conclusion would be to extend the enquiry by looking into the possible effects if I were to use different types of wire. A possible procedure would be to set up a similar experiment to the one I used in this current investigation but test 5 different types of wire which would give a possible variety to the amount of resistance produced and compare them to one another. Now knowing that as the piece of wire gets longer as so does the amount of resistance produced I would be able to support this conclusion with the additional evidence to how the type of wire can affect the outcome of resistance.
I can say with confidence that my investigation into the resistance in a wire was most successful. I have proven fact that resistance doubles in according to length and this is what I have learnt. It has provided my with enough information to be able to establish a foundation to investigate further and developed and interest into this issue.