# The Effect of the Number of Coils on an Electromagnet On Its Strength

Aim: ? To establish whether a variation in the number of coils willaffect an electromagnet?s strength.Scientific Knowledge: -The concept of electromagnets is fairly simple.An iron nail wrapped in a series of coils of insulated wire and thenconnected to a battery, will enable the nail to pick up paper clips.This is because the current emitted from the battery to the coilsmagnetises the nail. This is known as an electromagnet. The currentpassing through an electromagnet produces a magnetic field. Therefore,the more turns of the coil you have, the greater the magnetic fieldand the stronger the electromagnet.This will mean more paper clips being picked up by the nail. The strength of an electromagnet can also be altered by varying the current or voltage. The more induced voltage, the stronger the electromagnet. An alternative way to strengthen an electromagnet is to replace the core with a ?soft? iron core. Prediction: - An increase in the number of coils applied to the iron nail will cause an increase in the number of paperclips being picked up. (a positive correlation between the two variables) This prediction derived from the scientific knowledge above - ?Therefore, the more turns of the coil you have, the greater the magnetic field and the stronger the electromagnet.? Apparatus: - Iron nail (1) Paperclips (several) Power supply (1) Coil (1) Method: - The method was relatively systematic. We first allocated various people amongst our group to collect different equipment such as the iron nail, paperclips, coil and power supply. Following that, we connected everything securely and wrapped the coil five times around the nail. We then switched on the power supply and set the voltage to 4V. We tested the number of paper clips the nail would pick up, each time turning the power supply off and winding the coil five more times consecutively. Fair test procedures: - In the investigation, we controlled three main variables to ensure that our results were as accurate as possible.- 1) The voltage We sustained the voltage to 4V all the way throughout the investigation. This would make the test more fair. 2) Distance between each coil We made sure that each coil was 1.5 centimetres apart so that the current would flow evenly along the nail. This would also mean that the power of the magnetic fields around the iron nail were equal - each part of the nail would have the same magnetism. 3) Nail and paperclips Another factor of accuracy we took into account was to make sure that all the paper clips were of the same size and that we used the same iron nail throughout the whole investigation. This would prevent uneven results and would mean more accurate findings. For precision, we repeated the investigation again for comprehensive analysis and more accuracy. Results: - First Results No. of coils -????- No. of paperclips supported 5 4 10 fluctuation with results 11 15 [image]16 20 19 25 [image]26 30 42 35 36 anomaly [image][image][image] Second Results No. of coils -????- No. of paperclips supported 5 4 10 9 15 13 20 18 25 25 30 31 35 35 [image] We can infer from the positive correlation evident in this scatter graph that the number of coils is proportional to the number of paperclips attracted, thus, the number of coils is proportional to the strength of the electromagnet. Analysis: - In the first set of results, there was an abnormal fluctuation of the number of paperclips supported by the iron nail. When 30 coils were wrapped around the iron nail, 42 paperclips were magnetised, but when 35 coils were wrapped around the iron nail, the number of paperclips supported dropped to 36. The method of spacing the coils out evenly along the iron nail only became apparent in the reiteration of the investigation. Therefore it would seem that this considerable flaw caused the sudden fluctuation and made the results irregular. ? The difference between the number of paper clips being picked up each time were irregular as shown below: No. of paperclips supported 4 11 16 19 26 42 36 Irregular differences 7 5 3 7 17 -6 In the second set of results, when there appeared absolutely no anomalous results or figures of irregular nature. ? The differences between the number of paper clips being picked up each time were similar as shown below: No. of paperclips supported 4 9 13 18 25 31 35 Similar differences 5 4 5 7 6 4 Average ? (5+4+5+7+6+4) = 5 (1 s.f.) [image] 6 The number of paperclips supported increases by 5 (on average) as 5 more coils are added each time. Conclusion: - As more coils are added to the iron nail, the stronger the magnetic field and therefore the more amount of paperclips it can pick up each time. This scientific theory complements my second set of results to a great extent as more paperclips were attracted each time when more coils were applied. I am sure that this conclusion is correct as there were no anomalous results or irregular differences between the number of paperclips attracted when more coils were added each time. Evaluation: - Overall, I think the investigation I carried out was seemingly accurate, especially for the second run through. I do think however, that my investigation could have been improved by carrying out a third reiteration, with the coils distanced equally apart. This would then confirm my initial prediction and my results. In the first set of results, there appeared one anomaly. I am quite certain that this happened due to the uneven distance between each coil along the iron nail because in the second set of results, there appeared no anomalous results. In terms of further work, I think I could have used additional apparatus such as a Hall Probe to produce much more reliable results. By using the Hall probe, I could have recorded the strength of the magnetic field each time 5 more coils were added. This would have significantly enhanced my investigation as I could see whether the magnetic field legitimately grows stronger as more coils are added rather than trusting mere theoretical information.

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