Investigating_the_Resistance_in_Veriuos_Lengths_of_Wire

My physics coursework will be based on the conduction of an experiment. This experiment is about the resistance of different lengths and the thickness of different wires. The factors that I must consider whilst doing this coursework are: thickness, length material, temperature, voltage and current. I will only be varying the thickness, material, and length of the wires. Three different types of thickness will be tested; these different types of thickness will be tested separately. The length of the wires will be controlled in 10 cm gaps, from 100-0cm, this will be done three times 2 each wire. I will make sure that the current stays the same. I’m doing this to keep it a fair test. The equipment that I will use will be: · 1 metre stick · 1 metre length of wire · 1 power pack (set to d.c. 0-13 volts) · 1 voltmetre (0-5 volts) or (0-10 volts) · 1 ammetre (0-14 amps) · 1 variable resistor (0-16 ohms) · 1 pair of crocodile clips [IMAGE] The method in which I am going to take out this experiment is that for a start I will set it up, and check that everything is ok, and running as it should. Then I will begin monitoring the voltmetre taking my results down on a rough piece of paper. From 100cm - 0cm, altering the variable resistor as each step is taking place, this is make sure that the resistance stays the same, making it a fair test. When I have reached 0cm I then go back up again 100cm, and once I have done this I will come back down again to 0cm, recording all of my findings. After this I will change my wire for another one, and begin the test again. I will do this for three different wires. For safety I will ensure that: · I conduct the experiment nowhere near water of any sort. · I turn the power off after I take a reading; this is to make sure that the wire doesn’t get too hot. · I keep all of the wires separate, and not tangled or bare. To make sure that I get as a curate results as I can possibly achieve I will go from 100cm – 0cm three times so that afterwards I can use an average of my results, and if a mistake is made then it is very easy to pick up. I predict that the longer and the thinner the wire the higher resistance there will be. This is basically because, in length terms, the more atoms that the electrons has to pass through the higher the resistance. Eg. [IMAGE] Text Box: The longer the wire, the more atoms are found within that length of wire. So if electrons want to easily pass through the wire then they are going to need the most direct route they can find, so if there are more atoms present then the more collisions will be made and the least direct route can be taken. Also I predict that the thinner the wire is the more resistance will take place as well. Although there are more atoms, it gives the electrons more space, and monuverability. Eg. [IMAGE] My preliminary work helped me come to this prediction as well, as the results I found from it sugested that my prediction is correct. The thicker wires had less resistance and the shorter the length of wire, again the less resistance. Analysis My graphs show that resistance is proportional to length. This is because of the straight line that can be seen with a positive correlation. As shown here in a table of results taken from one of the graphs. 26 SWG-Nicrome: =============== Wire length (cm) Resistance (ohms) 25 1.65 50 3.35 75 5.00 100 6.75 30 SWG-Nicrome: Wire length (cm) Resistance (ohms) 25 3.50 50 7.20 75 10.70 100 14.40 34 SWG-Nicrome: Wire length (cm) Resistance (ohms) 25 6.40 50 12.80 75 19.40 100 25.80 Text Box: The longer the wire, the more atoms are present and the more atoms the electrons have to get past, when the electrons are colliding with these atoms it slows them down, causing the resistance. So an electron will pass through a short piece of wire faster than a long one. As was explained earlier. [IMAGE]This shows that resistance is proportional to length, because the longer the length the higher the resistance. That goes with all of the graphs. This diagram was shown earlier in the plan section of the coursework. My conclusion does support my original prediction, as not only does the resistance go up when the wire is longer but it also does when the wire is thicker as well. Thickness of wire End resistance 26 SWG-Nicrome -------------- 6.75 30 SWG-Nicrome -------------- 14.40 34 SWG-Nicrome 25.80 This shows that the thicker the wire the more resistance occurs. Therefore my prediction was completely correct. Evaluation I think that the investigation went very well over all, not many problems, and I got the results I had hoped for. Although errors did occur, as shown on the graphs by circles around them, they could of occurred in a number of different ways, such as: · Results being taken down incorrectly · Results being set out incorrectly · Faulty equipment · Misreading of graphs, etc. The method and procedure that we used was very good, the results found were very substantial and useful, I think they were plenty enough to support my conclusion. The only real way that we could of improved it would be to use digital equipment so to get a more accurate reading each time we took down results. There were error readings, but not many, and they didn’t really affect the outcome of the experiment. The only real way in which I could further the support for my conclusion would be to do more tests, with different wires, and different types of wires, not just sticking to Nicrome, but moving on to different wires.