Resistance of a Wire †Triple Science Essay

I also will be measuring the wire using a meter ruler and will be keeping the temperature down by keeping the power pack level at 2volts. Apparatus 1. 1 Metre Ruler 2. 1 Power Pack 3. Sellotape 4. Variable Resistor 5. Ammeter 6. Voltmeter 7. Constantan wire Method I connected my circuit together as shown in the diagram above. I attached the wire to the meter ruler using pins. As I carried on doing the experiment I adjusted some of the wires to make sure everything was correct and in place. Steps: 1. Adjust one metre length of constantan wire onto the metre ruler, and added the pins. 2. Adjust and connect all the wires together 3. Turning on the power pack. The voltage and current are then read off the ammeter and voltmeter 4. The power supply then turned off, and the crocodile clip moved to the next position I counted the seconds of how long the power pack was on for to test for the investigation, my partner then read the results, and wrote it down, while I moved the clip to the next position. I double checked my results, making sure I was close to the true value, so I had no outliers. Results. When doing my experiment on the different lengths of the wire, I double checked everything, to ensure that everything was correct, and there was no in-corrections. I recorded my results in the table below: Length (cm) Voltage (V) Current (I) Resistance (a ¦) Voltage (V) Current (I) Resistance (a ¦) Voltage (V) Current (I) Resistance (a ¦) 1I saw that I had no outliers. I then calculated the means of the voltage, current and then from that calculated the resistance (V/I). R1 R2 R3 Mean Range From the tests and my graph, I acknowledged that the longer the wire, the larger the resistance. My graph gives a positive correlation. When I doubled the length of the wire, the resistance also doubled, for example, when the wire was 10cm, the resistance was 0. 15 (a ¦), When the wire is 20cm, the resistance was 0. 31cm. Therefore, the fact that the resistance increases with the length, I have gathered that the longer the piece of the wire, the further the electrons have to travel, which means there are more ions for the electrons to bump into, so when the length of the wire doubles, the more ions there are for the electrons to bump into, which makes the resistance increase. As the length increases, the resistance of the current increases because the current has further to go through in the wire, thus it has to go past more stationary atoms, which cause more collisions, and therefore there is more resistance. However, I believe that my results are reasonably reliable, because i repeated my experiment twice, and i double checked my calculations for the mean. My line on the graph, were mainly on the best line of fit. Fair Test To ensure that my tests and results were fair, I had to keep variable the same. The variables that I had to keep the same where the temperature of the wire, due to the face that the wire gained more thermal energy as the ions began to vibrate (This would sometimes become a problem when the wire was ‘10cm’, because the wire was not as long.) However it seemed to be fine, which was expected because I chose ‘constantan’, which is proven to have a very low temperature increase. Another factor that I had to keep the same is the material of the wire because depending on the material, each material conducts different amounts of heat, which would affect the resistance. Reliability To make sure that my readings were all reliable, I had to double check and repeat my experiment again, so that I could spot any errors in my results. Using the wide range of lengths from 10cm to 1 metre allowed me to get a good range of results so that I could make a good conclusion. Accuracy To make sure that my test was accurate, I had to control the various procedures of the tests. One way in which I did this, was to measure the length of the constantan. The reason why I did this is to make sure that all my tests were accurate, and that my results would be close to the true value, or at least reliable. Safety To make sure that all the tests are done safely, the power pack settings will be under 5 volts, so that the constantan wire will not get too hot and burn. If I did not take this safety measure into consideration then it could damage and affect the experiment, and give un-reliable results. Also all bags and outdoor clothing will be away from the experiment, in case any heat causes any accidents. Evaluation At the start of the investigation, I don’t believe that I started off to well, as I was behind the rest of my peers, because my partner and I was a bit confused. However, when I understood what I was doing, I soon caught up, and was off to a flying start. The length investigations went very smoothly. I did find that sometimes, it was quite difficult to be accurate with whether the tip of the crocodile clip was exactly on the measurement I wanted, because it would make around etc. One way I could have made sure that I was doing this accurately, was to make sure I pinpointed, If I had ensured this, I would have got more accurate readings, and much more precise measurements. Copper Atoms Electrons 3rd Test 2nd Test 1st Test Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.