WIRES:
Different wires have different lengths and thickness, and they also have different resistance. Some wires will allow more current to pass through, making the resistance low and some may allow less current, which will cause a higher resistance. Also the longer the wire, the bigger the resistance. The shorter the wire, the smaller the resistance. And the thicker the wire the less resistance there will be.
For this investigation we were given two wires, and they were nichrome and constantan wires.
I chose not to use the nichrome wire because it is effected by heat. This is because if I chose this wire then it would not be a fair test as the wire is affected by heat and will not give me good results.
But for my experiment I chose the constantan wire because it is not affected by heat. I have chosen this wire because this wire is not affected by heat and will be a fair test and should give me good results.
So to round it up I did not use the nichrome wire because it is affected by heat, and I chose to use the constantan wire because it is not affected by heat.
PRELIMINARY RESULTS:
Before I had started my experiment I took down some preliminary results, from a preliminary experiment. For this I had to make a parallel circuit, using a resistor instead of a light bulb.
For the series one I added another resistor in a straight line next to each other, and for the parallel one I will also add resistors as well. To make it a fair test I will use the same voltage for every experiment I do.
This is a table to shoe my preliminary results for a series circuit.
This is a table to show my preliminary results for a parallel circuit.
PREDICTION:
Before I actually start my experiment I will make a few predictions. I predict that the resistance will increase, to the length of the wire. I will also predict that the shorter the wire, the current will have to pass though fewer ions and there will be fewer collisions. I would also say that the longer the wire the bigger the resistance will be, and the shorter the wire, the smaller the resistance will be. I will also predict the wider the wire; there will be more electrons that will flow. And the smaller the width of the wire, there will be less electrons flowing. I also predict that if the wire gets heated, the atoms will start to vibrate so it will be harder for the electrons to travel. Because the heat can affect the experiment, like room temperature I will not be using, heat affects nichrom wire as it. So for that reason I will be using the Constantan wire, because it is not affected by heat at all.
APPARATUS:
1-Two 1-meter rulers
2-Wires
3-Crocodile clips
4- Mirorometer
5-A voltmeter
6-An ammeter
7-Constantan wire
8-Power pack
9-Gloves
10-sellotape
11-A calculator
APPARATUS DRAWN:
Constantan wire
Sellotape
Wires
Crocodile clips
2, 1-meter
Rulers
Mirorometer
Power pack
VARIABLES:
The variable that I will be changing is the length in which the current has to pass through the constantan wire. I will try to keep the measurement as accurate as possible, by using the meter rulers. I will also use the same piece of constantan wire, so that the thickness on the wire will be the same, so that my experiment will be a fair test if the wires thickness will be the same. I will also keep the voltage the same throughout the whole experiment, also to make it a fair test.
The factors that will affect resistance are the following:
1- Temperature
2- Material
3- Length
4- Width
SAFETY:
Before I will even start my experiment, I will make sure that the area that I will be working in should be clean, and I will make sure that I will put my coat on the hanger to avoid me or any one else falling over it. And I will also make sure that I will put my bag under the table properly, so that it will also avoid me or any one else falling or tripping over and getting hurt. I will also make sure that I will be wearing gloves because I am working were there is electricity is involved. I will also be wearing gloves because the wire I am using may be sharp, so that if it is sharp then I want cut myself because I am wearing the gloves. Also for safety reasons I will make sure that I will not run in the lab, because I can hurt my self or even other people, and I may even ruined my experiment or someone else’s experiment.
FAIR TEST:
I will make my experiment a fair test by doing the following things. I will keep the voltage the same throughout the whole experiment; I will be keeping it on 4 volts. The voltage should be kept the same because if the voltage is put higher, then there will be an increase with the temperature, so the higher temperature will cause more collision and there will be more resistance. Also if the temperature has increased then it will not be obeying ohms law, as the temperature must remain the same to obey it.
I will also be using a micrometer to measure the thickness of the wire, which can also affect the resistance. I will also use the same ammeter, the same voltmeter, I will also use the same crocodile clips and I will also use the same power pack. I will also try to complete my experiment all on the same day, so that the temperature is the same through out all of my experiments. This is needed to be done, so I can compare the results and achieve good reliable average results.
I will also try to avoid parallax errors. This is when the readings are not taken straight on, but are taken by and angle. I will try my best to avoid this error, as it will give me unreliable results. I will try to take the readings looking straight into the voltmeter and the ammeter.
I will try my best to do all of these things in my experiment, so I can make sure that my experiment will be a fair test.
I will also do the whole experiment again; I will do the experiment again so I will now if I get any anomalous result. When I do the whole experiment again I will make sure that I am using the same apparatus, so that I am making the experiment a fair test.
METHOD:
Before I start my experiment I will make sure that the area that I am working at it is clean. I will also make sore that I have hanged my coat away, and that I have put my bag under the table. I have done that for safety reasons, so I will not trip or fall or get hurt at all.
First of all I will get all of the apparatus that I will need for this experiment. Then I will connect the wire to the power pack, so that I have power supply. Then I will connect an ammeter to one side of the wire, and then connect the voltmeter to the other. Then I will get two, one-meter rulers and join them together using sellotape. After I have done that I will get the constantan wire, and measure the width of it by using a micrometer to get the thickness of the wire. Before I stretch the wire I will make so that I have made the wire straight, because if the wire is bended in places it will not be a fair test. Once I have done that I will stretch out the wire so that it will be two meters long. Then I will stick the wire down using sellotape, on to the two one-meter rulers and will make sure that the wire is stuck down properly and cannot move. Then I will connect one end of the constantan wire to the ammeter using a wire and a crocodile clip, and the other end of it will be connected to a voltmeter, which will be in the opposite direction of the power pack.
Once I have done all of that I will start to take down my results in a results table. I will be taking down my results, at every 10 cm until I reach 200 cm (2 meters). I will be doing the same experiment twice. When I have done the experiment two times I will be working out an average resistance, for all of the lengths from 10 cm to 200 cm (2 meters). This will help me work out any odd result, which may have occurred due to human errors. Then I will write in all of my results in a results table, and will also write in the average resistance in a table as well. Then I will plot the points of the average resistance results in a graph.
I will work out the resistance by dividing the current to the voltage. To work them out I will be using a calculator. And this is how I am going to do my experiment.
OBTAINING EVIDENCE:
This is a results table to show the results I got in my first experiment, and it also shows the resistance.
This is a results table to show the results I got in my second experiment, and it also
Shows the resistance.
This is a table to show my average results for resistance. (These are the points that I will be using to plot my graph).
I have worked out these average results by adding together both of the resistance for each different length, and then dividing by two. All of these readings are given in 2 decimal places.
I did take full advantages on the apparatus that I was provided with, and I had used them correctly and used them safely.
I now that I took down enough readings to allow me to make a convinced conclusion. I have said this because by looking at my graph I can see that they my results follow the same pattern.
ANALYSIS:
By looking at my graphs, I can see that as the length of the wire increase, the resistance also increases and as the length of the wire decrease the resistance also decreases. These results do agree with my prediction, because I said the longer the wire will be the bigger the resistance will be. And I also said that the shorter the length of the wire the smaller the resistance.
From looking at the data that I have collected from my experiment I can clearly see that the resistance does increase as the length of the wire increases. This proves that my hypothesise was correct, as it stated the longer the piece of the wire the higher the resistance. As there are more positive ions in the wire, stopping the free negative electrons going pass.
I had only got a few anomalous results and did not really affect my flow or results. On my graph I constructed the line of best fit on my graph. By looking at my line of best fit, I could see that most on my results were right but some were a bit funny. On my graph I have circled the anomalous results that I got.
EVALUATION:
By looking back at my graph, there were a few results that I did not agree with my line of best fit. The reasons that I may have got anomalous results and why they may have happened are, parallax error. I have said this because I may have read the voltmeter or the ammeter, at an angle and for that reasons I may have worked out the resistance wrong. Also the temperature may have changed, and for that reasons I may have got anomalous results for that. And if the temperature changed this will cause more collision with the ions. I also may have done a calculator error. I have said this because I may have typed the wrong buttons on the calculator, but I did check my results twice so I could see if I had done a mistake, while using the calculator. Also that the wire that we were using may have had a bump or may be bent in some places, which would change the thickness of the wire and therefore may even, affect the resistance. The results of experiment one may differ to experiment two, because they were done on different days. But by looking back at my results I can clearly see that, doing my experiment on two different days did not really differ my results.
I think that the way I done my method worked well. And I can also see that doing my experiment two times really helped, because then I could see if I had got any anomalous results.
I can saw that I may have had a few problems, because when I had to stick the two one meter rulers together, I really had to make sure that I had stuck them properly without giving extra or less millimetres or centimetres. I also had to check that in the wire there were no bumps or bents in it. So I had to straighten the wire before I had done the experiment. So to solve this problem I measured the wire every 20 cm using a micrometer.
I think that if I were to do this whole experiment again and improve it, I would do theses following things. I would have used an electrical ammeter and an electrical voltmeter. I would use an electrical ammeter and voltmeter, because then I would have given me the right number of the current and the voltage. Because I had read the readings, I may have made a human error by reading it wrong. I would have also have used smaller crocodile clips. I have said this because the crocodile clips that we had used were thick, and they may have affected the resistance. I also could have done the experiment one more time, because I only done it two time. I would have like to do it one more time so I could see if I had got any anomalous results. And also I could have used a straighter wire, because the wire that we had got had bumps and it was bent in places. And I had to straighten out the wire my self, and I could have miss parts that needed to be straighten. And if the wire was bent then it may have affected the resistance.
On my graph I got a few anomalous results and I circled them on the grape. I may have got these anomalous results because I may have read the ammeter or the voltmeter wrong, or I may have type the wrong numbers on the calculator when I was working out the average resistance.
I have found ways that I could have extended this investigation. I could have found out what affects resistance, I also could have investigated on how the width of the wire affects resistance, how different materials, affect resistance and how temperature could affect resistance.
Overall I think that I have carried out a successful investigation. And I am also pleased that I was able to meet my aim, in order to carry out this investigation.
DIAGRAM OF WIRES:
If the wire is longer, it will have more ions in it. For that reason, there will be more resistance because the wire is long, so there will be more chance of collision.
The thicker the wire the routes, in which the current can pass through. The current can pass more easily. For that reason if the wire is thicker, the resistance will be low. If the temperature would increase, then the ions will vibrate more. When the ions would vibrate more, then there will be more collision. When the collision will take place, it would create a higher resistance.