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This experiment has worked well and has produced sufficient results that produce quite an interesting conclusion. I did not have any unusual and anomalous results. However, the methods used were not in such way that gives the most reliable results, as, the coils were not done in exactly the same way, so the length of the coils inside the magnetic field is not precisely the same in all cases. A mechanical device could be utilized instead of doing it by hand. The results, however, are not strictly and totally accurate, as the circuit itself is not 100% efficient. The resistance inside the wires drains up some of the energy. Some flux of the magnetic field can also be lost through the magnet's shape, for instance – bended wire around the nail at the end. From this, a high expectation cannot be made from such inefficient system because there is no solution to gain total efficiency. Analysing Evidence & Drawing conclusions To draw a conclusion from my graph, first of all I would divide it into Three sections: Section A (the bottom), section B (the middle) and section C (the top). This would now make it easier to describe. The first section (A) looks like it does because for the amount of current put in, only a few of the domains had lined up. My second reading that I took was inaccurate, so on my graph I have circled it, and discluded it in the drawing of the curve. The graph then gets steeper (section B), this is because all of the domains are now lining up. As the strength of The current goes up, the strength of the electromagnet goes up directly proportionate to it. In section C, all of the domains had lined up. Section C was not drawn in on my graph because of the fact that there was not enough of a wide range of readings available to be taken with the apparatus that I was given. The graph was not what we had expected, as I wrote in my planning that I was expecting to be drawing a straight line graph. This prediction was wrong because we had not expected the domains to take time to line up. We thought that they would line up straight away. In the experiment, the current changed quicker as it increased per centimeter we pushed the variable resistor. This made it fluctuate more, and it was therefore harder to be able to obtain accurate readings. After we had been carrying out the experiment for a while, the bar may have retained a bit of magnetism if a large enough current was put through. There was also a change in the temperature of the bar-it heated up. When doing the experiment we made sure that we turned it off after taking each reading so as we kept control of the temperature in the experiment and to avoid it heating up and affecting the experiment, making it unfair. There was less chance of getting an anomale in the experiment because we took an average of the three results. It was a reasonably accurate experiment, and if I repeated it I would get similar results. I can justify all but the third section on my graph (C) because I didn¡¦t go to a high enough voltage, but if I did I would have obtained the ¡§leveling off zone¡¨ because other people using a high enough voltage did. If I wanted to make some improvements to the experiment, I would take the results five times, and to a greater degree of accuracy of current and weight loss (four decimal places or more). We also could have tried to keep the temperature more constant by not leaving the current on between the takings of readings and leaving it to cool. We should also have zeroed the To extend the investigation I could have tried varying the number of coils, or another factor, keeping the current constant, then another variable and comparing the results of varying those others. I could also have tried using iron filings for an example to see if different results were given When insulated wire is wrapped round an iron nail and the ends of the wire are connected to a battery the nail becomes capable of picking up iron filings and paper clips. This is called an electromagnet. The nail is magnetised by the current in the wire. If the battery is disconnected then the iron clips will fall off. This is because most of the magnetism has been lost. The passage of an electric current along a wire creates a magnetic field around the wire. The fields are in the shape of a series of concentric rings. The more coils used in the electromagnet, the stronger the magnet is. If there is one coil, and another is added, then the two coils have twice the strength of one. This is because the current going through the wire makes the soft-iron core is the factor that induces electromagnetism, as so when there is more current, there will be more wire or or a more magnetised core. Magnets were formed when certain molten metals, (iron, nickel and cobalt,) cool . Normally when the atoms in a non magnetic crystallise, the atoms point in random directions. But because of the properties of the metals mentioned, these atoms line up into parts of the magnetic with similar directions called domains. This is because the earth has a magnetic field, and the atoms in the metal all follow the these magnetic lines and form these domains. This is similar to what happens when an electromagnet is formed. I think that the more current that goes through the wire, the greater the electromagnetic pull of the soft-iron core will be. This is because the current going through the wire makes the soft-iron core is the factor that induces electromagnetism, as so when there is more current, there will be more electromagnetism. This is the same with the the number of coils,ed with the electromagnet, the more power is returned. The return and investment are not directly proportional. I think this because of the aforementioned scientific knowledge. 1) Current- This will change in one experiment. This will be kept constant by observing the ammeter and correcting any fluctuations on the D.C power pack. 2) Magnetic strength of the Soft-Iron Core. This will affect the power of theelectromagnet. It will be kept constant by using the same soft-iron core. 3)Way in which the wire is coiled. If the coils are coiled towards end, then one end will be more powerful than the other, and affect the results. I will try to keep the shape of the coils uniform. 4) Way in which the iron filings are shaken. The harder the the magnet is shaken, then the more iron filings will be dropped, and the more the weight will change. Here there is a very clear curve a the beginning, but the final three amps there is a similar per amp rate of increase suggesting that unlike experiment 2. This shows that one amp does increase the magnetic power one unit- the more expended, the same return on the investment. It is dissimilar to a thermistor current vs. resistance graph, and similar to a resistor current vs. resistance graph. The Scientific Explanation-Experiment 1 As the current is passed on to the wire, it becomes a magnet itself, in accordance with the right hand rule. It magnetises the ÔsubstanceÕ at the core. Inside the ÔsubstanceÕ there are domains. When they are magnetised they aligned themselves onto the same direction , making it magnetic, This needs energy to perform and maintain the process, it is not cumulative so the more energy put into it the more will come out. This is similar to experiment one, except there is a curve is. Here there is a very clear curve. It starts very closely and then raises increasingly rapidly. It starts of very slowly and then as more power is put in, it rises faster and faster. This shows that one coil does not increase the magnetic power one unit- the m The number of coil around an electromagnet is not proportional to the electromagnetic strength. When more coils are in contact with the core, which is what the experiment shows, more area of interaction is available, allowing more domains to be magnetised quicker than if the area is smaller. So if there is more area, the magnetic area will become stronger. there is a kind of activation energy. The four factors that affect the resistance of a piece of wire: In the Analysis and the graph I have shown two main anomalous points, this means that there must have been a slight error in my experiment. As the wire, length is bigger at these points I found it harder to stretch it out and consequently, measure it accurately. Although the graph is overall accurate and the results precise it is easy to see, the anomalous averages plotted because they do not all lie along the same best-fit line. The graph shows that my results are reliable as there are only two main anomalous points, (which are easily accounted for) to improve the reliability of my results, I could do more repeats in doing this my average would be more reliable. As I increased the wire length, the wire became hotter and gave off heat. This could explain why the anomalous results are at the top of my graph, 100cm and 95cm. I think one of the reasons why my experiment is quite accurate is because I tried to measure the wire as accurately as possible. The metre rule was selotaped onto the workbench. The wire was stretched until it was nearly in a straight line so a bit was overlapping at each end. As the metre rule was curved and worn down at the corners it was slightly hard to see where 0cm was. Finally, the inside edge of the crocodile clips were placed at the appropriate point. I still however would like to make the measuring more accurate Key Factors which could affect this experiment were : The metal that the core is made of. The accuracy of the amount of electricity being used. If the pins in the box are magnetised. If the core stays a permanent magnet after the electricity is turned off. If all the pins were made of the same metal. Because 0 pins should be attracted at 0 volts, I added a data point for 0,0 on the graph. This makes the best fit line more accurate. The results showed in bold are anomalous because they do not fit in with the pattern that the other results follow. The experiment may not have been a completely fair test, as we observed that the iron nail would attract about 1-2 pins when the electricity was turned off. This meant that the nail did become slightly magnetised but only by a small amount. The results did show that my predictions had been right. The amount of pins increased with increasing voltage, but the amount of pins started to stop increasing when the voltage was at 8 volts. This was probably because the electromagnet had almost reached the Magnetic Saturation point (i.e. it had almost attracted all that it could). The results also seemed to show a trend in the way they increased. Every time the voltage was increased by 1 volt, the amount picked up increased by roughly 2 grams. Probably the reason that some of the results were anomalous was because the voltage used wasn't precisely accurate as the dials on the Power Packs can be misread slightly. Also, some of the pins may have become magnetised, or the nail may have become a weak permanent magnet. These reasons could also account for the spread of data in the other results. My best fit line didn't pass through the origin, although it came very close. This is probably because the iron nail which was used as a core was slightly magnetised and therefore acted as a weak permanent magnet, before the electricity was turned on. Bibliography: Word Count: 2139
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