Wire affects its resistance Essay Example for Free

Wire affects its resistance Essay Current: Current is the movement of electrical charge the flow of electrons through the electronic circuit. Current is measured in AMPERES (A). A current is a flow of electrons, the higher the current the more electrons flow round the circuit every second. Batteries can make electrons move. They can push electrons through wires made of copper and other metals. Materials like copper let electrons flow through are called conductors. The tiny electrons squeeze between the atoms in the wire. Some materials stop electrons passing through, these are called insulators. Plastics and rubber are insulators. The voltage will be measured so I will be able to calculate the resistance using Ohms Law. The current will be kept the same throughout the experiment and then will be used also to help me find the resistance using Ohms Law. (`Wires Wires warm up when a current flows through. Thin wires warm up much more than thick ones, and some types of wires warm up more than others. They warm up because of collisions inside the wire generating heat. If too much current were passed through a wire it would melt. (`ElectricityElectricity is lots of tiny particles called electrons moving along a wire. Electrons are much smaller then atoms. In fact, they are parts of atoms, so there are electrons in everything. (`Circuit A circuit is a path for electrons to flow through. The path is from a negative terminal power source, through the various components and onto the positive terminal. Think of it as a circle, the paths may split of here and there, but they always form a line from the negative to the positive. NOTE: Negatively charged electrons in a conductor are attracted to the positive side of the power source. This helped me to set up my circuit. ( `Conductor A conductor is a material (usually a metal) that allows electrical current to pass easily through. The current is made up of electrons. This is apposed to an insulator, which prevents the flow of electricity through it. Even good conductors have some resistance to flow through it. The conductor that I am going to use is copper wire, which has resistance. Electrons need energy from the power source (in this case a power pack) to travel. The further they have to travel, the more energy it takes so the resistance increases. In Metals The Current Is Carried By Electrons 1. Electric current will only flow if there are charges, which can freely move. 2. Metals contain a sea of Free Electrons (which are negatively charged). And flow throughout the metal if they are given energy. 3. This is what allows electric current to flow so well in materials. ( `Resistance Resistance is anything that causes an opposition to the flow of electricity in a circuit. It is used to control the amount of voltage and /or amperage in a circuit. Everything in a circuit causes a resistance (even wire). It is measured in OHMS (? ). Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire. The resistance of a wire depends on the number of collisions the electrons have with the atoms there will a larger number of collisions which will increase the resistance of the wire. If a length of a wire contains a certain number of atoms, when that length is increased the number of atoms will also increase. E. g. If there is a wire that is half the length of another wire it would also have half the number of atoms, this means that the electrons will collide with the atoms half the amount of times. Also if the length of the wire is trebled or quadrupled then the resistance would also treble or quadrupled. My prediction was derived from this information. All of this information I collected originated from the Website, www. studentcentral. co. uk from encyclopaedias such as The Oxford Childrens Encyclopaedia and computer encyclopaedias such as Encarta. (This scientific information relates to my experiment by stating that the longer the lengths of wire the higher the resistance. (Preliminary Results Length Of Wire (mm): Voltage (V): Current (A): Resistance (? ). (Therefore this information supports my prediction that the longer the length of wire the higher the resistance. Obtaining Evidence: (The variables I kept the same are: (The same material used for the wire, (The same cross-sectional area of wire, (And the same temperature of the wire. (The potential difference from the power pack: 2V. (The current, which measured the rheostat, was kept at: 0. 5A. (The lengths of the copper wire: (0 mm, (100 mm, (200 mm, (300 mm, (400 mm, (500 mm, (600 mm, (700 mm, (800 mm, (900 mm, (1000 mm. (The readings from the voltmeter and the ammeter were measured to two decimal places. Test One: Length Of Wire (mm): Voltage (V): Current (A): (These tests are reliable because you can see patterns, which is as the length increased the resistance increased. (It is a suitable range of lengths because I have done over six sets of results (0 1000 millimetres), so I will be able to identify a line of best fit to show my results. (My results are accurate, as they show as the length of the wire increased the resistance increased proportional to it. Averages: Length Of Wire (mm):Voltage (V): Current (A): Resistance (? ). (To find the resistance I divided the voltage by the current, e. g. Length of wire 100mm: Resistance = 0. 02 0. 5 Resistance = 0. 04 ? (My results show as the length of the wire increased the resistance increased proportional to it. I know this because my graph shows a fairly strong positive correlation, which tells me that as the length of the wire increases the resistance of the wire increases, proportional to it. (Also my results show when I started at zero (0 millimetres) it was a good control to show no change. (The results were not exactly proportional as I expected, but the graph still justices my prediction that as the length increases the resistance increases also. This was because the longer the wire the more electrons there were, subsequently it was more likely that the electrons were going to collide with other electrons, thus there was a higher resistance. (The resistance depends on the number of collisions there were between the atoms of the material, which was copper. The length of the wire affects the resistance because the number of atoms in the wire increases as the length of the wire increases in proportion. Hence there is a higher resistance. Evaluating Evidence: (I think that the procedure of the experiment was fairly accurate as I recorded my results to two decimal places and also because on my average table of results the increase in resistance could be easily identified. Overall I think that my procedure during the investigation was well planned out. (The main problem I had was when I was reading the ammeter and the voltmeter as the readings kept fluctuating and took time for the readings to settle down, which as a result affected my results. (The ranges between my results were small and fairly close on the tables, which indicated accuracy. Although when I converted my results into a line graph I found that six out of the eleven results were anomalous results, which was probably due to human error and probably due to defaults in the meters, as they were battery powered. Also the sensitivity of the meters as they were not very sensitive and therefore my results were affected by this. (Even though there were anomalous results they were fairly close to the line of best fit as they were either just above or just below the line of best fit. Therefore the results were quite accurate and so I felt that I did not need to repeat any of the results and that I did not need to record any more results, as the results still justified my prediction. (Furthermore I could have changed the line of best fit so that more of the results fitted in with the line. (The improvements I could have made to make the results more accurate would be to use a much more sensitive ammeter and voltmeter, so I could have recorded my results to three or four decimal places, which would have made my results more accurate. Moreover I could have had shorter length ranges to show better accurate results, to see how a small increase in length affected the resistance compared to a large increase in length. So I could have use the range of lengths from zero millimetres to twenty millimetres to 40 millimetres and so on rather than the range I chose, which was zero millimetres to 100 millimetres to 2000 millimetres and so on, which therefore would have affected the results (resistance). As a result this would have shown the pattern better, clearer and easier to point out and it would have improved the line of best fit. Wednesday 27th 2001 F. Nazmin Hussain 10. E.