The Effect of Increasing Number of Turns in a Coil on an Electromagnet It Is Capable of Holding

The Effect of Increasing Number of Turns in a Coil on an Electromagnet It Is Capable of Holding
Introduction In this investigation I aim to find out what effect increasing the number of turns in a coil on an electromagnet will have on the strength of the electromagnet, and the weight it is capable of holding. I predict that the higher the number of turns there is on the core the higher the amount of weight the magnet will hold. Also I predict that, if I double the amount of turns in the coil on the core, the magnetic field strength of the electromagnet will also double, I will find out if this is true from the weight it is capable of holding. E.g.) 20 turns will hold 50 grams 40 turns I predict will therefore hold 100 grams Above is a predicted example of what I think might happen when I increase the numbers of turns in a coil on an electromagnet. I do not know that twenty turns will hold fifty grams, as this is just an estimated amount. Theory -?- In a piece of iron there are millions of tiny ?atomic magnets?, they are called this because in each atomic magnet there is a North and a South Pole. In the piece of iron these tiny atomic magnets line up with each other in small groups, when they do this they become domains. In a piece of iron, that is unmagnetised, the domains will all point in different directions, see diagram 1 below, the domains are shown by small arrows, the arrowhead indicates the North Pole. As all the domains are pointing in different directions there will be no true north seeking or south-seeking pole in the piece of iron as the domains will cancel each other out, therefore the piece of iron will remain unmagnetised.
But, when the piece of iron becomes magnetised, the tiny domains will all turn to point the same direction. This will give the piece of iron a true north-seeking pole and a true south-seeking pole; the piece of iron will have become a magnet. To achieve this magnetism the North Pole of another magnet needs to be stroked along the length of the piece of iron. This causes the domains to be pulled by the magnetic force into place so they are pointing the same direction. See diagram 2 below. [image] 1. Unmagnetised Iron 2. Magnetised Iron In conclusion to this theory I believe that if I were to break a magnetized piece of iron in half I would find that either piece of the magnetic iron would still act as a magnet. This is because all the domains that are inside the iron would still be pointing in the same direction as they were before the break. This means there will be an even number of south-seeking poles to north-seeking poles; it will still remain a magnet. For my experiment I will be making a magnet, not by stroking it but by passing an electric current through its magnetic field, this process works in a slightly different way. One turn of wire acts like a magnet, once it is linked up with a battery and has a current flowing through it, the single turn will have a magnetic field. This can be proven by passing a turn of wire through a piece of card, then sprinkling iron fillings on the card, once the current flows though the wire the iron filings will show the shape of the wire?s magnetic field. The field shape is very spaced out, weak and in large circles, it would take a very long time for this to magnetize a core. A compass can be used to find the direction of the field. Then I would change the shape of the single turn to a long, thin, and compact coil, which is also known as a solenoid. I would now repeat the above experiment with the iron fillings, from this I can see that the shape of the magnetic field is very familiar, as it is the same as the one of a bar magnet. I would also notice that inside the solenoid the magnetic field would be very strong and uniform, the field is more in tight ovals rather than widely spaced circles, it is this field that magnetizes a piece of iron when it is placed inside the solenoid. One end of the solenoid will act as a North Pole, the other a South Pole we can find this when we put a small magnet inside the solenoid, as it will point north. When the soft iron bar is placed inside the solenoid it will make the magnetic field stronger and larger; consequently it will enable the magnet to hold a larger weight than before. This happens because the solenoid has the same effect to the piece of metal as a magnet does when it strokes the metal. The domains in the piece of iron will therefore line up and point the same direction causing the piece of metal to become magnetized; hence the new magnet has a magnetic field around it, as does the solenoid. These forces combine and together they make the magnet stronger. The magnetization of the core reaches saturation once all the domains are completely aligned and an increase in current or turns in the coil at this point would have very little further effect. When the current is switched off the core retains a very weak residual magnetism. It is this that I will be investigating in my experiment. I will be finding out if the number of coils has any effect on the strength of the magnetic field of my magnet when I test it with weights. From the scientific knowledge above, I have already proved that the more coils there are and the closer they are together the larger the magnetic field strength. Therefore my prediction that the strength of the magnet doubles as the number of turns on the core doubles, I feel is probably correct. Pretest Aim The aim of my pretest is to find a suitable current and starting number of turns on an electromagnet to be used in my main experiment. The aim for my main experiment is, does the number of turns on an electromagnet affect the field strength and the weight it is capable of holding? Apparatus ? U-shaped soft iron core ? 8 meters of wire ? Power pack ? 3 leads ? Ammeter ? Wire cutters and strippers ? Clamp stand ? 10g and 100g weights ? Nail ? 2 crocodile clips Diagram Method ? Set up all apparatus as shown in the diagram on the previous page. ? Firstly, I will set the ammeter at 1A with only ten turns on the electromagnet, then using weights I will measure how much the electromagnet can hold and then record this result in a table. ? Still with only ten turns on the electromagnet I will increase the current to 2A. Again by hanging weights from the magnet I will find out how much it can hold, I will record this result in my table ? I shall now do the same again for 3A ? Now, I shall increase the number of turns to twenty, I will now test how much the electromagnet can hold at 1A, 2A and 3A, all the results that I receive I will record in the table. ? Again, I shall increase the number of turns to thirty; I will now test how much the electromagnet can hold at 1A, 2A and 3A, all the results that I receive I will record in the table. Table of Results Number of turns Current (Amps) on the coil 1A 2A 3A 10 0g 0g 50g 20 0g 40g 70g 30 30g 80g 150g The table above shows the current and the number of turns I have used. The weights in the middle show how strong the electromagnet was in grams. From this information I have decided to use 3A as the current in my main experiment. This is because I feel 1A and 2A are too low to get accurate results. 3A is perfect as it is strong enough to get good and accurate results and it is also not too hot to melt the wire as any amount larger than 3A could. This is why I did not try 4A and above as I did not want the wire to burn out and cause any accidents. I will also start the main experiment at 20 turns on the electromagnet. This is because; as we can see from out pretest that it is the lowest amount of turns which will holds a steady amount. I did not want to start at 10 turns, as it is unpredictable that the coil would have any affect on the soft iron core and I would definitely get a result. The range I will use in the main experiment starts from 20 turns and ends at 100 turns, I will be going up in tens this will give me nine results. Nine results enable me to plot a successful graph, find any patterns that may emerge and also find any anomalous results. I will measure the strength of the electromagnet by placing a nail across the ends of the u-shaped iron core. Then I will hang the weights from this. I will do this experiment three times, therefor for each number of turns there are on the electromagnet I will gain three results showing how much it can hold. This will give me accurate and reliable results, which I will subtract the anomalies from. The only variables that will change as the experiment goes are, the number of turns on the electromagnet, this is because I will be testing the effect these have on the electromagnet. The other is the amount of weights I will put on the electromagnet; these will change because I will be adding more to find the weight the magnet is capable of holding. All of the other factors that could be variables if I wanted them to be will be kept the same throughout the main experiment. These factors are: ? Same soft iron core ? Same length of wire ? Same current of 3A ? Same nail ? Same method of measuring the strength of the magnet ? Same temperature ? Same method of putting the weights on the magnet ? Same amount of area covered by turns I have expressed these factors more fully in the main method under the sub heading fair test. Main Method Apparatus ? U-shaped soft iron core ? 8 meters of wire ? Power pack ? 3 leads ? Ammeter ? Wire cutters and strippers ? Clamp stand ? 10g and 100g weights ? Nail ? 2 crocodile clips Diagram Step by step instructions ? Set up all apparatus as shown on the previous page in the diagram. Make sure to only have 20 turns on the coil and have the ammeter set at 3A to start with. ? Place a nail to the top of the u-shaped core, it should be held in place, as the core will be magnetic. ? Using ten-gram weights and a hook, I will hang them off the nail. I will carry on placing weights on the nail until the magnet is unable to hold them any more. At this point the weights should drop off the magnet, as they are too heavy. ? Then I will record this weight in a table. ? Then I will release the core from the clamp and wrap ten more turns around the core, I must keep the ammeter reading 3A at all times. Again I will hang weights off the nail, and record the total weight that the magnet is capable of holding. ? I will carry on adding ten turns to the coil until I have 100 turns in the coil, every time I get a result I will record it in my table. ? To achieve accurate and reliable results I will repeat the whole experiment twice again so I will have obtained three results for each number of coils on the electromagnet. Variables These are the only factors that I will be changing throughout my experiment, the factors I will keep the same I have stated in my fair test. The only changes that I will be making to the experiment is the number of coils on the core, I will do this by taking the electromagnet out of the clamps and wrapping ten more turns on to it, and then replacing it. I will also have to change the weight that I put on the electromagnet; I will have to keep adding ten grams until the nail falls off the magnet. I will do this because it will find the strength of the electromagnet. Range As I am only finding out what effect the number of coils has on an electromagnet, I will not be changing the current that I use, therefore I will keep this at 3A at all times. I found out this range from my pretest, I wanted to go up in 10s so there is a large enough difference between results and not too large difference, as I don?t want the magnet to become fully magnetized too soon. In my opinion nine results is enough to plot a good graph and to find a general pattern. I didn?t start at 10 turns as this didn?t hold any weights, I didn?t want to go any more than 100 as I found the coil was getting too hot and could burn out. The range that I will be using for my experiment is: Number of turns 20 30 40 50 60 70 80 90 100 Fair Test In my experiment I will keep these variables the same in order to keep my experiment fair. If I changed any one of these factors throughout my experiment I would find that it changes my results and the experiment is no longer a fair test. ? I will use the same piece of wire to create the turns in the coil so that the thickness and length will not change. If either of these factors was to change there may be an increase in resistance this could decrease the strength of the electromagnet, therefore a weaker magnet is produced. ? I will use the same nail because different nails might be attracted to magnets easier than other nails. A rusty nail will not be as attracted as a clean, shiny one would be. ? I will use the same u-shaped core in my experiment so that the size does not change. A large core would take loner to magnetize than a small one and might also hold more than a small core; therefore we would get different and unfair results. I will use an iron core because this magnetizes and demagnetizes quickly, whereas steel takes time and would not give me accurate results. ? I will have to use the same method of measuring the magnetic force of the magnet I have decided to use ten-gram weights because weights would give me an answer in grams straight away; a Newton meter would give an answer in Newton?s. This is not a problem as I could easily use a conversion graph to convert my results; although with a Newton meter you must read off the strength very quickly and can easily been mistaken therefore I will use weights in my experiment, as it is more reliable. ? I will keep the current the same as I am only testing to find the effect the number of coils has on an electromagnet. The current must not be too low as the results would be inaccurate but not too high as it might trip the power pack and burn out the wire. I will use 3A; I found this from my pretest results. ? I will try to keep the coil of wire at the same temperature throughout, as I do not want the wire to burn and melt its plastic coating, as this is dangerous. I will do this by allowing a cool down period where I will turn off the current and leave it for a few minutes. It will be impossible for me to keep the temperature exactly the same at all times but I feel that the temperature will not affect my results greatly. ? Another important factor I will keep the same is the method I put the weights on the electromagnet, if I put them all on gently instead of dropping them on I will find that my results will be much more accurate. I will also I will also add ten gram weights not 100, as ten grams is much more precise. ? I must also try to keep the area that the turns on the electromagnet at the same size throughout, by doing this it will ensure that the concentration of magnetic fields stays the same. I need to do this as more concentrated turns will provide more strength to the electromagnet. Reliability In my experiment I need to know that my results are reliable and correct. To do this I will need to repeat my experiment three times, so for every time I add ten coils I will test to find out how much the electromagnet can hold, I will test it three times. In my opinion I think it would be best to do one whole experiment and add ten turns each time and then go back to the beginning again, rather than measuring each ten turns three times. I think this will make my results fair and more accurate. Accuracy I will find out if my results are accurate by looking at the difference of weight between each result, I am referring to all three results taken for example at twenty turns. I will know if my results are accurate as they will be close together, similar or even identical. If results are identical then I know that there are more than likely to be correct, it would be very unusual if three results were almost the same and all to be wrong. By following the fair test values I hope to find that my results are close together and very accurate. Analysis ? Table of Results Anomalous results Number of Turns Weight Held (g) in the coil Experiment 1 Experiment 2 Experiment3 Average 20 50 60 50 53 30 200 80 100 90 40 110 120 130 120 50 210 180 190 193 60 220 230 240 230 70 360 320 340 340 80 400 410 420 410 90 450 490 460 467 100 540 580 560 560 Graphs and Tables Analysis As you have just seen I have produced a table of results and two graphs. My table shows the range of the number of turns I have used, the results I obtained from my three experiments and it also shows an average that I have worked out. My table shows any anomalous results that I have subtracted from my average, this will keep my results accurate. On my first graph I have shown all three results I have obtained for each ten turns that I added, this makes it much easier to find any anomalies, which I have circled. My second graph shows all the averages of the three results for each ten turns; in this graph I have subtracted the anomalies. For each graph I have added a curved line of best fit, this shows the general sequence of the weight that an electromagnet can hold. It also helps if I wanted to find out how much an electromagnet would hold with 35 turns for example, I would simply be able to read this information off my graph and I would find it could hold 95 grams. I predicted that my graph would be a straight-line graph, I have looked at my graph of averages and I have added a line of best fit. I have done this freehand; therefore; the line of best fit is a curve. The line is, although it is not shown on the graph starts at the origin and becomes very shallow at the start, I feel it I shallow because the magnetism was not strong enough to start with and was having no affect on the domains. It begins to increase in gradient and later becomes very steep or proportional and continues this pattern until I stopped investigating. This shows that the iron core starts to magnetize slowly and will not hold a large force when there is a small coil around the core. Its field strength increases when the coil grows larger; it is now able to hold a larger force. From my graph of averages I feel that the weight held for 60 turns was too low and should be slightly higher, this is something I could assess again if I was to repeat the experiment. I feel I have received these results because, in a piece of iron that is unmagnetised, the domains will all point in different directions. As they are doing this there is no true north seeking or south-seeking pole in the piece of iron as the domains cancel each other out, therefore the piece of iron will remain unmagnetised. But, when I magnetized the piece of iron, the tiny domains turned to point the same direction. This will give the piece of iron a true north-seeking pole and a true south-seeking pole; the piece of iron will have become a magnet. But I stopped my experiment before all the domains had chance to point in the same direction, if they were to have done I could say my magnet had saturated. Because I stopped I never knew when my magnet would have saturated, to find this I will need to extend my range, I predict that once the magnet saturated I feel the line of best fit on my graph would curve and then continue at a horizontal line. In my experiment I have made a magnet, not by stroking it with another magnet, but by passing an electric current through its magnetic field. This process works in a slightly different way, but still causes the domains to be pulled by the magnetic force into place so they are pointing the same direction. One turn of wire acts like a magnet, once it is linked up with a battery and has a current flowing through it, the single turn will have a magnetic field. The wire?s magnetic field shape is very spaced out, weak and in large circles, it would take a very long time for this to magnetize a core. For my experiment I changed the shape of the single turn to a long, thin, and compact coil, which is known as a solenoid. I have noticed that inside the solenoid the magnetic field is very strong and uniform, the field is more in tight ovals rather than widely spaced circles, it is this field that magnetizes a piece of iron when it was placed inside the solenoid. One end of the solenoid acted as a North Pole, the other a South Pole. When the iron bar is placed inside the solenoid it will make the magnetic field stronger and larger; consequently it enables the magnet to hold a larger weight than before. This happens because the solenoid has the same effect to the piece of metal as a magnet does when it strokes the metal. The domains in the piece of metal will therefore line up and point the same direction causing the piece of metal to become magnetized; hence the new magnet has a magnetic field around it, as does the solenoid. These forces combined and together they made the magnet stronger. This is how I received my results, my results from the graph and the theory link and show me that the more coils there are on an electromagnet the stronger it will be. This theory is true but only until the magnetism of the core reaches saturation when all the domains are completely aligned, at this point an increase in current or the number of coils would make no difference or have little further effect. This would be shown on the graph as a straight horizontal line. It is clear that from my results that my electromagnet was no way near saturation and if I had carried on increasing the number of coils I would have found that eventually my graph would have straightened out. In conclusion to this, I predicted that the higher number of turns there is on the core the higher the amount of weight the magnet will hold, I have come to the conclusion that this is correct as I have stated in the above paragraph and in my theory. Also I predicted that, if I doubled the amount of turns in the coil on the core, the strength of the electromagnet will also double, I would then find out if this was true from the weight it was capable of holding. E.g.) 20 turns will hold 50 grams 40 turns I predict will therefore hold 100 grams Above is what I thought might happen when I increased the number of turns in a coil on an electromagnet. When I predicted this I did not know that twenty turns would hold fifty grams, as this was just an estimated amount. From my experiment my results concluded that this was not true, I found that the doubled number of coils far exceeded its predicted amount of weight it was possible of holding. E.g.) 20 turns on average held 53 grams whereas 40 turns on average held 120 grams. If this experiment had followed my prediction 40 turns would have held 106 grams. This one example is although very close to the predicted amount, it is not exact. Yet further down my table of results I found a much larger gap between the two results. E.g.) 50 turns on average held 193 grams whereas 100 turns on average held 560 grams Here there is a large gap of 174 grams, if my results matched my prediction this gap would not be here. I feel this is because an electromagnet has a compound effect on the field strength when more coils are added; this makes it difficult to establish the exact relationship between the number of coils and the magnetic field strength. Evaluation Accuracy I feel that from my experiment, the results that I received were very accurate and all followed an obvious pattern. I think that the results were very good as they all were very similar and close together, in my opinion, this was because I tested each number of coils three times each. If results are close together, similar or identical then this shows that they are clear and truthful answers, they are very possible to be correct. It was very rare that results differed more that 30g away from each other. This shows me that the results I was getting were very accurate as it would be very unlikely for me to get three results which all proved to be wrong. An example of my results are, for 20 turns, the results gained were 50, 60 and 50, these all very in close proximity. Another way than just looking at a table to see if the results are close and clear, is to look at the graph I produced, as you can see the results I have plotted follow a clear pattern, a smooth curve that straightens out, my results accurately inhabit a line of best fit. I feel this has happened due to the fact I kept to my fair testing rules throughout. If I was to improve to make my results more accurate I would extend my range, see experimental procedures on the next page. Anomalous Results These are also know as pattern breakers as they will fall out of pattern with other results I have gained. In my experiment I only found one anomalous result, this individual was much higher than the results I gained in the two other tests and also what was expected. I feel this happened because I might have not checked that the variables were not set correctly, such as the current was higher than 3V, also the number of coils could also have been higher due to carelessness or I did not follow a fair test value, which are all ment to be kept the same at all times, as carefully as I should have done. I feel that the sudden increase in strength of the electromagnet was due to temperature, the rise in temperature came from the wires getting hot, the rise will have caused this sudden surge in energy. Reliability From my results I feel that they were good enough to support a firm conclusion, from these I agree that I was wrong in my prediction to state that as the number of coils doubled so did the weight the electromagnet could hold. From the results I was gaining I could easily see that the numbers were not following the pattern I had predicted E.g.) 50 turns on average held 193 grams whereas 100 turns on average held 560 grams Instead, I conclude that I know that an electromagnet has a compound effect on the field strength when more coils are added; this makes it difficult to establish the exact relationship between the number of coils and the magnetic field strength. Although by using my graph I could predict how many coils I would need to hold 350grams, 75 is the answer, there is no pattern, such as the one I predicted, between 75 turns and 350grams but from looking at my graph it is easy to establish any values needed. I feel my results strongly reflect and support my conclusion. Experimental Procedure I personally feel that my experimental procedure was excellent as I stuck to the fair test values that helped me produce accurate and reliable results. Although the method I used to find out the results, how much the electromagnet could hold, was not as reliable as I would have hoped. Instead of ten-gram weights, I could have used drawing pines or paperclips; by doing this I would have gained more concise results and the strength to a more accurate number or weight. Another way I could have improved my readings, the strength to a more accurate number, would to place an iron bar on a pair of scales then increase the strength of the electromagnet by adding more coils an investigate to see if the iron bar gets lighter. I agree it would, as the force of the electromagnet will cause it to do so, by using this method I would gain exact numbers and my results would be more accurate. If I had decided to look at the magnetic field strength instead of the electromagnet strength I could have used a compass, I would move the compass at shot distances away from the electromagnet until the compass was first effected by the magnet If I was to keep the same method I would pay more attention to the temperature and try keep it the same throughout my experiment as I felt this let me down and affected my experiments results, I would do this by testing the temperature of the surrounding area of the electromagnet and only carry out my experiment when the temperature was within a small, decided range. I could have put the electromagnet in water but make sure that all wires were well insulated. I also feel I might not have paid enough attention to the area that the number of coils covered, with a small number of coils a smaller surface area of the iron core was covered than with a lager number of coils, also the more concentrated the magnetic fields were the more powerful the field strength. This factor will have definitely affected my results. To improve my testing I feel I should have marked out an area upon the iron bar, the wires could only cover this given area even if it meant the turns to be stacked upon on another. To improve my experiment I feel I should have expended the range in two different ways. Both ways would improve my data and gain me a better understanding of the line of best fit on my graph. I would this by adding a smaller number of coils each time. Instead of ten I would go up in fives, this would show in more detail the exact course the graph takes. The other way would to extend the range, in would carry going up in tens (or fives) until I found the point when my electromagnet saturated, all the domains were pointing in the same direction, in the graph this would be when the line of best fit flattens to become a horizontal line. Further work To further my investigation I would still keep to the same aim, to find out what effect increasing the number of turns in a coil on an electromagnet will have on the strength of the electromagnet, and the weight it is capable of holding, but change certain values to understand how these effected my results. Firstly I would definitely extend my range as I have already mentioned in my experimental procedure. I would add a smaller number of turns each time to my electromagnet so that my results would be more accurate and also so that I knew that the line of best fit on my graph was more truthful and reliable. I would also extend my range so that that I would find out two different issues. Firstly I would try my electromagnet with no coils to find out if it had any electromagnetism before I even started, as this factor would have caused some alterations on my results. The second would be to extend my range in the opposite direction, go further than 100 turns, by doing this I would find out when the magnet saturated, this is when all the tiny domain inside a magnet has turned to face the same direction, this will be the magnets greatest strength. As the magnet saturated I would find that the line of best fit on my graph would become a horizontal line. I felt the temperature affected my experiments results, as I was not watching this factor throughout my experiment, as it is very hard to control. If I was to repeat my experiment I would eliminate the possibility of the temperature affecting the results, I would do this by testing the temperature of the surrounding area of the electromagnet and only carry out my experiment when the temperature was within a small and decided range. I could put the electromagnet in a water bath and make sure that all wires were well insulated and the temperature was not too high, possibly around room temperature. I would then hang weights from the electromagnet that was still inside the water bath and record my results. I would have to take into consideration the fact that the water will reduce the weight of the ten-gram weights, as the water will have up-thrust. I could also change the method in which I measured the strength of the electromagnet; instead of using ten-gram weights I could use drawing pins or paper clips. These both would give me an exact weight that the electromagnet was capable of holding. I could use a compass instead of weights, I would move the compass nearer and a slow speed toward the electromagnet, I would record the distance from the electromagnet the compass was when it was affected. This method would not be suitable for my experiment, as it would not conclude my aim. To investigate further I would see what affect thicker wires, yet the same amount of current, had on he electromagnet. I feel that there possibly would be no affect but I might be wrong, therefore I should find out. I will also investigate the concentration of the wires, I think I will find that the smaller the concentration, the area the wires cover on the soft iron core, the more powerful the electromagnet will prove to be. I will do this by investigating with the area the wires cover on the core; I will then test the results I gain three times each and record then. I shall look for any obvious patterns.

The Effect of Increasing Number of Turns in a Coil on an Electromagnet It Is Capable of Holding 7.6 of 10 on the basis of 777 Review.